Exclude item in automatic index

Question

Based on the question here, I used the following code

\DeclareCiteCommand{\footfullcite}[\mkbibfootnote]
  {\usebibmacro{prenote}}
  {\usebibmacro{citeindex}%
   \usedriver
     {\DeclareNameAlias{sortname}{default}}
     {\thefield{entrytype}}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

for generating an index of the authors of my document. Unfortunately, I am studying an author and I cite it many times in the text its name appears a lot of time in the index.

Is there any solution to hide a specific entry in the index automatically? :-)

MWE:

\documentclass[english]{article} 
\listfiles
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@ARTICLE{article,
  author = {Nachname, Vorname},
  title = {Titel des Zeitschriftenartikels},
  journal = {Zeitschrift},
  year = {2006},
  volume = {6},
  pages = {19--75}
}
@BOOK{book,
  author = {Buchautor, Hans-Wilhelm},
  title = {Irgendein Buch},
  address = {Buch am Wald},
  year = {2000}
}
\end{filecontents}
\usepackage{babel,csquotes}

\usepackage[
texindy
]{indextools}
\makeindex
\makeindex[columnseprule,intoc=true,title=Index,name=perso]


\usepackage[
  style=authortitle,
    indexing=true
]{biblatex}
\bibliography{\jobname}

\DeclareCiteCommand{\footfullcite}[\mkbibfootnote]
  {\usebibmacro{prenote}}
  {\usebibmacro{citeindex}%
   \usedriver
     {\DeclareNameAlias{sortname}{default}}
     {\thefield{entrytype}}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

\DeclareIndexNameFormat{default}{%
\nameparts{#1}%
\usebibmacro{index:name}%
{\index[perso]}%
{\namepartfamily}%
{\namepartgiveni}%
% {}% L1
% {}% L2
{\namepartprefix}% generates spurious space L3
{\namepartsuffix}% generates spurious space L4
}

\begin{document}
\index[perso]{check}
\index[perso]{checkb} 
\index[perso]{check} 
\index[perso]{checkb} 
\index[perso]{checkb}
\footcite{book}\newpage
\footfullcite{book}\newpage
\cite{article}\newpage
\footcite{article}\newpage
\footfullcite{article}
\printbibliography
\printindex[perso]
\end{document}

Answer 1

It is not quite clear to me what entries you want to exclude. But you can add rather easily a test to the citeindex macro:

\renewbibmacro*{citeindex}{%
  \ifciteindex
    {\iffieldequalstr{entrykey}{book}{}
      {\indexnames{labelname}%
       \indexfield{indextitle}}}
    {}}

Answer 2

There might be a better alternative to do this, but you could assign a category to a key which shouldn't cause an index. Sadly, this requires a change of all used citation macros. The following applies this change to the definition of \footfullcite you provided. Note that the key still shows up in the index for the page of the bibliography:

\documentclass[english]{article} 
%\listfiles
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@ARTICLE{article,
  author = {Nachname, Vorname},
  title = {Titel des Zeitschriftenartikels},
  journal = {Zeitschrift},
  year = {2006},
  volume = {6},
  pages = {19--75},
}
@BOOK{book,
  author = {Buchautor, Hans-Wilhelm},
  title = {Irgendein Buch},
  address = {Buch am Wald},
  year = {2000}
}
\end{filecontents}
\usepackage{babel,csquotes}

\usepackage[
texindy
]{indextools}
\makeindex
\makeindex[columnseprule,intoc=true,title=Index,name=perso]


\usepackage[
  style=authortitle,
    indexing=true
]{biblatex}
\bibliography{\jobname}
\DeclareBibliographyCategory{noindex}% create the new category
\addtocategory{noindex}{book}% add the key `book` to that category


\DeclareCiteCommand{\footfullcite}[\mkbibfootnote]
  {\usebibmacro{prenote}}
  {\ifcategory{noindex}{}{\usebibmacro{citeindex}}% only if not in noindex
   \usedriver
     {\DeclareNameAlias{sortname}{default}}
     {\thefield{entrytype}}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

\DeclareIndexNameFormat{default}{%
\nameparts{#1}%
\usebibmacro{index:name}%
{\index[perso]}%
{\namepartfamily}%
{\namepartgiveni}%
% {}% L1
% {}% L2
{\namepartprefix}% generates spurious space L3
{\namepartsuffix}% generates spurious space L4
}

\begin{document}
\footfullcite{book}\newpage
\footfullcite{book}\newpage
\footfullcite{article}\newpage
\footfullcite{article}\newpage
\footfullcite{article}
\printbibliography
\printindex[perso]
\end{document}

To remove the key entirely from the index, you could insert the \ifcategory check in the \DeclareIndexNameFormat-definition:

\DeclareIndexNameFormat{default}{%
\ifcategory{noindex}{}{
\nameparts{#1}%
\usebibmacro{index:name}%
{\index[perso]}%
{\namepartfamily}%
{\namepartgiveni}%
% {}% L1
% {}% L2
{\namepartprefix}% generates spurious space L3
{\namepartsuffix}% generates spurious space L4
}}

You could do the same based on the bib file and not inside of the tex-file by introducing a keyword if you like that approach more. The contents of the \jobname.bib file become:

\begin{filecontents}{\jobname.bib}
@ARTICLE{article,
  author = {Nachname, Vorname},
  title = {Titel des Zeitschriftenartikels},
  journal = {Zeitschrift},
  year = {2006},
  volume = {6},
  pages = {19--75},
}
@BOOK{book,
  author = {Buchautor, Hans-Wilhelm},
  title = {Irgendein Buch},
  address = {Buch am Wald},
  year = {2000},
  keywords = {noindex}
}
\end{filecontents}

Just change the check \ifcategory to \ifkeyword the rest remains untouched.