Perhaps there's some context I'm missing, but I don't see anything of particular note there. If anything, he wasted a pawn to just go back and let you develop for free. It's just that, well, you happened to move the pawn that was blocking their bishop from taking your rook. It's something that's happened to everyone before.
Though I completely understand the frustration, it seems to me that you're attributing a lot of motivations and traits to a random stranger you don't know, simply because they played a gambit and didn't follow it up how you expected them (or yourself in their situation) to.
No, you guys stop treating chess as a stall game. Hence why bullet and blitz are 2 of the worse variants. Let's stall or just move random pieces in an attempt to make my opponent timeout. Let's eat all my opponents pieces when I could have checkmated them 15 moves ago. Rated or Unrated. They're childish tactics that have become meta because people copy and paste what someone else used successfully. Then you just sit there laugh and try to troll your opponent during or after the game. Chess is about skill and the ability to see and adapt as the game progresses. Many of you treat it like Fortnite and live sports where trash talking and "getting inside someone's head" are "staples" to be competitive. Bet a lot of you would flop onto the floor in a real chess game hoping to draw a foul...
Thats everyy game too not just chess. It's just the sad point the world has come to.