In general, there's nothing wrong with hosts showing their culture. And if this was a relatively benign tournament, I think people would have had less issue with what is in theory a gesture of respect and would take it at face value.
But it wasn't a benign tournament. It was a tournament brought about by corruption, built on modern slavery, in a country with vile anti-LGBT laws. One that in political and social terms was actually worse than people were expecting in advance given the unanticipated strong-arming around alcohol, in-stadium symbols and the one love armbands.
In that context, you would be extremely naive to still see this as a straightforward symbol of respect rather than being one final effort of hosts who bought the World Cup for self-promotion to use the World Cup for self promotion. It was one last reminder of everything that has stained this WC, unfortunately timed for a moment when everyone was just thinking about the football they'd just seen.
Without all that context there'd be nothing to it, but there is all that context. Just as without all that context I wouldn't have had such an urge to see someone slap Infantino.