1. It's just strange - everyone could see his brain evacuating the premises in an orderly fashion, suitcase in hand, well before he even got close to Alonso. I've never seen a moment of utter madness as serene, planned and unconcerned as that.
2. I can only assume the ref either thought he got the ball, or that he was as utterly perplexed by why it had occurred as everyone else in the stadium.
3. I also assume the VAR people were perplexed by it - really, it was one of those historic moments of befuddled bewilderment among all and sundry, including probably Gazzaniga himself. I bet he wouldn't be able to tell you why he did it himself, the mad bastard.