Even if Keiko is fine with it, everyone else won't be okay with it. I'm the one who's gonna get yelled at later.
Literal
Keiko-[honorific-さん] [subject-が] good [even-though-ても] everyone [subject-が] not-convinced-[explanatory-んです]. Later I [subject-が] be-yelled-at-[passive-れる][because-んだから].
Casual frustrated speech. ドヤされる is the passive of ドヤす ('to yell at, to berate, to chew out') — a rough colloquial/slangy verb. 俺 is masculine first-person. 納得する ('to be convinced, to accept') is central to Japanese social negotiation — consensus-building is culturally important. The speaker is caught between Keiko and the group and will bear the social cost.