Actually, it’s kind of make sense when you look at how every single main hero in that shot got their current life. Steve went back in time and stole a life with Peggy. Thor got Love through Gorr's wish. Loki escaped his actual death to become the God of Stories. The X-Men literally rewrote their timeline in Days of Future Past, and the Avengers broke reality using quantum time travel in Endgame.
To Doom, these heroes didn't save the universe, they cheated fate, altered time, and stole second chances for themselves while leaving worlds like his to burn from the resulting Incursions. Telling them give them back means he's coming to collapse those altered timelines, strip away their happy endings, and force them to pay the price for playing God. They are cooked and i think thanos will be back too.
unpopular opinion: the wizards crossover was shit. i didn’t even like it back then as a child bc i realized they never filmed it together. the real crossover was at the tipton hotel with hannah, raven, london, maddie, zack & cody.