Kon was in a perfect position to catch Nico's eye and make a little swooping gesture towards her with his hand where neither Eric (who was focused on her) or the crowd behind him could see.

Yes, he would break cover and fly to get her if she fell.

That other gesture towards Eric was a bit more violent. Like...snapping a neck.

Yes, he'd make Eric pay for making them have to break cover, too, if he had to.