Vegas can read some H.264 .MOV files without QuickTime. Maybe you can try reading them with QuickTime uninstalled.
Otherwise I can offer instructions for how to rewrap H.264 .MOV files into .MP4 files. That's the better way of reading QuickTime files in Vegas anyway, because QuickTime reads them with poor quality and incorrect levels.
Vegas bypasses Quicktime for many MOV files which contain AVC/H.264. Right click the media and look at the properties, General tab, and scroll down and see what the plug-in being used is. If qt7plug then Quicktime is being used. If compoundplug, or other, then Vegas is bypassing Quicktime.