Or the anger could symbolize frustration in the fact that any single flaw in a man is seen as a deal breaker meanwhile toxic women receive almost zero repercussions for their behavior.

It's incredibly frustrating to face constant rejection and constant hate toward your gender as a whole. Yet simply expressing these frustrations is labeled as the actions of an "incel" or a "misogynist" when the reality is the men these women aren't referring to are fed up with always being lumped in with the minority of men who commit the majority of the shit women bring up.

Anger can be acceptable if you consider that statement isn't just about you. If someone rejects me because I'm not their type, that's ok, but if you go around saying other singles are bad too, rather than admitting your standards are just high (which is fine), that's rude, especially if you're not one of the "good ones". My sister uses that phrase and it does mildly anger me, because from living with her I know she's immature (among other problems) and, to a lot of men, and especially the "good ones", I'd assume she is seen as a bad partner herself.

That being said, I do agree that the comic here is kind of forced, I only heard this being said while gossiping, and never as a form of rejection of a specific person.

That was more of an insult than a rejection. And even the rejection part of it was something she approached him for. You don't reject someone who never asked. It's either a complete lack of social awareness or deliberate cruelty on the girl's part.

So while I agree that anger isn't a great response to rejection in general, I think it's entirely understandable in this case and doesn't imply a sense of entitlement. A rude retort wouldn't be uncalled for here.

Also note that there is a difference between feeling anger and expressing it to intimidate. Intimidation (or worse) should not be a part of non-violent social interactions at all. Anger should be managed.

The final frame in this comic portrays strong anger at rejection

No, it doesn't. It shows mild anger at being insulted for no reason. Are you running on the assumption that he's asking her out in this scenario? The only rejection he got was unsolicited. Like if I walk up to the next woman in the street, ask if she's single and when she says "yes" I respond "nevermind, you're not good enough". Now she's upset and understandably so.

I'm in full agreement with your point, but this comic is not a representation of that in any way.