>>280606754
Technically, Bofoi himself completely burned his image for Genos before that in the meteor incident, as well as other of his behaviors such as not coming to the meetings of the S-class heroes, not coming to help against the alien invasion and only coming to get the weapons as soon as the ship crashed, not helping against the monster association and so on probably helped considerably in the ease with which Genos believed the accusations against him. Especially when even Saitama pointed out that he had no interest in helping after the meteor incident.
So yes, Bofoi is very much at fault for ruining his own image with his own behavior even without anyone doing anything.