Is there reason to grow angry at the man in a joint-decision abortion?

The other person does not really want a "discussion".  They just want you to agree with their point of view.

Your question is too vague. Gonna need a bit more context here.

Depends. Was it REALLY a "joint decision," or was the female only on board after the man said, "If you don't abort, I'm leaving you," or something along those lines? If so, then yes, there is very much reason to get mad.

If it actually was a joint decision from the getgo, it's possible that the female is grieving the loss of the baby (because that's what it was, a baby) and lashing out as a result of that grief.

That depends on exactly what you mean by 'joint decision'. Did both partners freely agree this was the best decision, or did he convince her with bullying, emotional manipulation and coercion when she didn't actually want the abortion? 

If you're the kind of person who gets angry about abortion then sure, he's not performing his role as gatekeeper to his partner's body.

If you're sensible then no.

There's no such thing as a joint decision abortion

Only if he's being mean about it - like it's an inconvenience that he has no part in. 

nope not at all