Another factor to consider is that Mogas vaporises much more readily than Avgas, as used to be demonstrated by pouring a thimbleful of each on a concrete floor. An even better demonstration is to prove how easily it vaporises in an ultralight fuel pump during a long climb with no electric pump backup. I still have the scars from the ensuing forced landing
Always sad to hear of any accident particularly when this should have been a joyous and much anticipated aviation occasion. My sympathies to the families of those who lost their lives.