One way you could get around this would be to have xenforo in a sub directory instead of your website root. That way both directories can have index.php your splash page just clicks through to /whateverfolder/index.php
that does not make any sense to me... it is stated in FAQ that index.php filename cannot be changed. Obviously programming logic of XenForo relies upon existence of index.php and its contents in order to function properly. But on the other hand the htaccess can be used to totally disable the system with a DirectoryIndex setting. They are two separate entities and htaccess should not be affecting XenForo like that. This is somewhat limiting is it not?
I don't think anyone was offended. Even being 2 seperate entities, when your webserver sees the the .htaaccess file it intercepts the call and forwards it, XenForo isn't doing that. A splash screen option within XF would be nice but we always have other options