Again, defensible if not particularly nuanced.
The guy just lost one of the biggest upsets in the last 20 years to a team, and in particular, a player, that absolutely balled out of control. He's pretty obviously trying to keep his negativity in line, gave a very reasonable answer to a very stupid question (we are all in agreement that it's a stupid question, I take it), and caught himself multiple times from getting personal with the reporter, even apologising at the end for snapping.
This is exactly what we should expect from NBA players. To be honest, Giannis is basically just riffing on the old Jordan quote about failure (I've missed 26 game winning shots &c).
Also "they're old" - Giannis is 28. He's five years younger than the guy who bounced him out and, unlike that guy, he's already got a ring. Are we really taking the position that Miami is going to have a brighter future than Milwaukee?