BuddyPress.org

I think you should just be able to put an HTML file at the root and it should load that index.html file instead of the BP index.php file. At least if the server that host your website has it set to load index.html before index.php (which should be the default for most I believe). The only exception might be if the permalinks changes to the .htaccess file somehow have it ignore the index.html and go straight to the php one.

Just try adding the index.html at the root of a BP install and you’ll find out really quickly.