I've no idea whether they would or wouldn't, my point though is that if he is teaching honestly then it's not fraud. He can certainly be teaching incompetently, badly, wrongly and a lot of other 'lys' but if he believes he's teaching it because it works ( and he had to have been taught by someone to do it) then we cannot accuse him of defrauding anyone.
Now a lot of others are also teaching badly including some in BJJ, I won't accuse them of fraud either. I've seen BJJ people who really do think that that all other styles are inferior, something they often accuse others in martial arts of doing.
What is annoying however is some people's assumption that only they 'test' their style, only they can say their style works because of that. The assumption that all karate schools teach the same thing and that it doesn't work is ridiculous, as most know there are many styles of karate including mine, Wado Ryu which includes take downs, grappling moves etc. It did since it's inception. There is a certain kind of arrogance in thinking that one knows it all because of just a few things one has seen.