No, it is not dishonest. Fabi said don’t trust Regan’s analysis. He also said that he didn’t think Hans cheated in that one game given the moves played (before Magnus gave his reasoning, so perhaps Fabi’s opinion would change). Fabi never said “Hans is not a cheater.” Rather, he argued it’s possible to cheat, and detection methods FIDE uses are not sufficient. If Hans is cheating, Fabi implied that Regan’s analysis likely wouldn’t catch it.

Magnus, Ian, and Hikaru at the very least have pretty openly (given the legal threats flying around) said/implied they believe Hans cheats, and chess.com has very explicitly said this.

Maybe not all of their comments and beliefs focus on this particular OTB game, but that’s not how you catch a cheater, since it’s rare to find a smoking gun. You look at a pattern of behavior. Hans has cheated in the past, and many top players believe he is cheating in some way, in at least some games, on a continued basis… which is why Magnus refuses to play Hans, and why we’re even having this discussion.