The reason I figured I'd be able to change to hidden abilities is that all pokemon are able to get them. Since the main games don't have that, I don't see any logical reason whatsoever that would suggest that for some reason hidden abilities for some reason shouldn't be able to be ability capsuled. If it's not a bug, then I think it should be fixed but I'm not the developer. However, neither are you, so we'll see if Silent Chord actually thinks it's a bug. Plus, I find that it's better to report things that might not be bugs than to not report them, since there is no harm done if a bug is reported that isn't a bug but if it is a bug it can be fixed. I often report bugs that could very well just be logical fallacies.
Edit: Found another potential bug, it seems like the trailer on Syringa beach can not be entered even though the door is open.