I did some looking around this morning at the major players in the space: Zoom, Microsoft Teams, Google Meet.
All have the ability to require MFA for meeting organizers, but I don't see where any offer the ability to require MFA for meeting participants.
That said, all of those other players offer the ability to have participants require sit in a "waiting room" until the organizer allows them to enter. In addition, for any meeting of significant size, all participants other than the organizer have their cameras blocked and their microphones muted.
There is always a delicate balance between security and usability. In Mark Kay's world, every participant in a remote meeting would require MFA. I've worked with enough non-tech savvy people to know that getting people to join a remote meeting can be challenging enough. Adding MFA to the mix will mean that several people won't figure out how to join.
Is it possible that Zerify Meet will find a niche where MFA for every meeting participant is justified? Maybe. But the revenues of that niche are unlikely to cover the salaries of the bloated management team.