It was definitely ambiguous, but
Aemond is super dutiful and about family. So he'd stand up for Aemond in public, even if privately he might think he's an immature frat boy (which is a nice parallel to Alicent explaining this principle to Aegon in the prior episode). And he definitely hasn't forgiven Jace/Luke for the past either, so he'll happily take a chance to get a punch in.
As for wanting the throne, he wouldn't usurp his brother. And I don't think he's motivated by power either. Even if Aegon died right now, I don't think he'd be like "**** yeah, now I get it" ... although he WOULD press his claim, the same way Stannis did. Because at that point he'd think it's his by rights.