Bonus actions in 5E ARE .... too decoupled from the fictional world.
When you write the effect that way, you're still "leaving it all for the DM to fix during gameplay". You say your wording makes it "clear" that you can't inspire while drinking a potion, but that's not actually what the words say: it's an interpretation which you're assuming the DM will make based on your notion of what constitutes common sense. And if we're assuming common sense, why can't we just say that it's common sense to figure out "what you are actually DOING" when you use this ability?Bonus actions in 5E ARE hacky and too decoupled from the fictional world. There's a lot of places in 5E where you get to do something "as a bonus action" but no consideration is given to what you are actually DOING. Bardic Inspiration is a poster child for this kind of ugliness. If bonus actions didn't exist, presumably the bard would have some kind of ability like "When you cast a spell through song, you can weave your words in such a way that [the ally gets bardic inspiration]." That would make it clear that (1) yes, Bardic Inspiration is compatible with spells that have verbal components; (2) you can't inspire others while gagged (even though you can cast spells while gagged, e.g. Hypnotic Pattern, because it has no Verbal components); (3) it would make it clear you can't inspire others with song while you are busy drinking a potion (Action: drink a potion) because your mouth is busy. The ability could be written in such a way as to be compatible or not compatible with other actions like hiding, attacking, or extra object manipulation as desired. The designer would be encouraged to consider in advance what the ability is really doing from a fictional perspective instead of just lazily slapping gamist "bonus action" jargon on the ability and ignoring the fiction, leaving it all for the DM to fix during gameplay.