I don't know that we should put *too* much stock in anything Abel says. His description of August is certainly plausible, but he doesn't provide any hard evidence for his speculation and Abel's motives are highly suspect.
That said, it's obvious pissing off August would be a bad idea, the question is what that would take. At the moment, his overriding priority seems to be bonding with Hana. He evidently thinks having the MC around the Club helps Hana feel comfortable. She likes the MC (the exact amount depending on our choices) and clearly feels better having him around - both as someone her age, and as a fellow newcomer trying to find their role in the place.
I suspect August is willing to tolerate a fair amount of disrespect as long as the MC continues to serve the main goal. If the MC should stop making Hana comfortable, that's when we'll need to walk a lot more carefully. And if the MC manages to piss Hana off enough to be a net discomfort to her, that's when things could quite literally end in blood.
All the more reason not to cheat on her.