É possível solucionar isso usando essa configuração:
<VirtualHost 127.0.0.1:80>
ServerName localhost
<Location "/">
Header set X-Intelligence "CLEVER"
</Location>
<LocationMatch "^/[^\.]+$">
Header set X-Intelligence "STUPID"
</LocationMatch>
<LocationMatch "^/(main|about)$">
Header set X-Intelligence "CLEVER"
</LocationMatch>
</VirtualHost>
Dessa forma, as seguintes solicitações funcionam conforme o esperado:
# curl -I -L http://127.0.0.1/ 2> /dev/null | grep X-I
X-Intelligence: CLEVER
# curl -I -L http://127.0.0.1/foo 2> /dev/null | grep X-I
X-Intelligence: STUPID
# curl -I -L http://127.0.0.1/about 2> /dev/null | grep X-I
X-Intelligence: CLEVER