As you said, it honestly depends upon the context and situation!
If I'm roleplaying with a realistic gaggle of friends in Flourite and we're approached by a 10-foot tall overlord of the underworld, it would honestly be a disruption if they tried to attack us; they'd completely derail our roleplay. Our current scene couldn't continue in the face of their power-trip and it would, admittedly, ruin what we were doing.
Whereas, if an oddly-coloured hyena approached our own, we could still acknowledge and interact with them-- even if it doesn't exactly align with our interests. As long as they make certain their actions aren't too disruptive, and understand when others reasonably express their concerns, I see no problem.
However, of all places, I definitely wouldn't expect 100% realism in Bonfire! When I roleplay there, I do take into account that dinosaurs, dragons, fauns, mermen and anime characters can, and will, approach you. Even so, the horse roleplayers can be an odd bunch; I'd take everything they say with a grain of salt.