In Trump’s world, the political utility of having a closet of conspiracy-crazed boomer rubes is worth the downsides.
Winning candidates often receive a congratulatory message from an incumbent president. It’s one of those pro forma niceties of the Old Washington, and Trump’s staff craves moments that make him look like something other than a ranting, gouty old racist, so tweeting “Congratulations to future Republican Star Marjorie Taylor Greene on a big Congressional primary win in Georgia against a very tough and smart opponent. Marjorie is strong on everything and never gives up – a real WINNER!” probably seemed like a good idea. Hell, Republican victories these days are few and far between.