Local .htaccess strangely allowed running PHP in CGI/FastCGI mode in Apache under shared hosting environment

The problem is not that Apache rewrite rules in the .htaccess file won't work when running PHP as a CGI vs. an Apache module. It's just you can't use the .htacess file to set PHP values when it's ran as a CGI. Instead you have to have a separate php.ini file that has your settings changed in it. Within my own shared hosting account, which runs PHP as a CGI, I make use of FastCGI and have the following in my .htaccess file:

<IfModule !mod_php.so>
    AddHandler myphp-script .php
    Action myphp-script /cgi-bin/myphp.fcgi
</IfModule>

Then in my accounts /cgi-bin/ directory I place the myphp.fcgi script with chmod 755 containing:

#!/bin/sh

# This ensures PHP doesn't try to run it's own
# process manager.  
export PHP_FCGI_CHILDREN=0

# Execute PHP with my php.ini config file
exec /path/to/system/cgi-bin/php -c ~/myconf/php.ini

I still have a <IfModule mod_rewrite.c> section in my .htaccess file to handle rewriting some old URI paths to the new URI structure to maintain old links that are cached in search engines.