Uh... Someone who talks about being trained specifically for a situation expecting people who haven't to react as if they did.. What could go wrong?

Contextually, the only correct part in that is to not draft unannounced or unwanted. Everything else is just "how it ought to be" conjecture.
There is no way of knowing what could happen if contact was made with an unknown rider, with unknown reactions, in a non closed circuit, non race setting. Maybe nothing, maybe only the rear rider goes down, maybe the forward person is sent headfirst into traffic.

There is a similar sight on freeways sometimes when some jackaninny thinks they are participating in an F1 race with others who are just commuting to work. Often the result of too much GTA. Usually they just look like jerks. Once in a while they cause a fender bender. Occasionally an ambulance gets called.

In the cycling sense it is usually caused by a wannabe or has been who has watched too much TDF and then hits the MUP instead of an actual organized ride to live out their racing fantasy. If people want to draft, find like minded riders. Don't creep strangers unannounced.

I like watching the Superbowl as much as the next guy - but it doesn't mean I want some unknown guy patting me on the hiney.