We can assume that he was just told not to do so or might be, he thinks that if only he's not like that, there will be no problem that happened last December where he failed to show up in the weigh-in because of his viral condition.
Anyhow, trash talk or hitting the opponent with some offensive words is not really necessary.
They can do the talking on the ring, not in exchange of words in the public.
Yeah, maybe someone is the background is advising Casimero to tone down a bit because it doesn't make sense at all to trash talk the likes of Inoue and Donaire. The fight will happen sooner or later. And he should learn from his fellow Filipino, the legendary Manny Pacquiao, who chooses to do the talking inside the ring and not being so arrogant outside and talking trash to his opponent.
I think Casimero has been always like that and people do know him that he always talk a lot even it is already nonsense at all. But we don't know about that now because maybe this time he figured out that it's time to wisen up and speak less and let his actions do the talking, or if that's not the case then his team has told him to be quiet for now and concentrate more about the preparations.
That is why he needs to wisen-up because lately he was always blabbing his mouth and it is not that effective anymore, Inoue is a Japanese boxer so Japanese is his first language and he won't definitely affected even if Casimero trashtalks him in pure straight english.
If Casimero really wants to be follow Pacman's footsteps or achieve more greater than him then I don't think his mouth can surely help him with that ambition. I mean, look at Pacquiao and Donaire.