Warren is part of the senate "fight club", the group of senators trying to oust Schumer and orchestrate a more progressive senate Dem leadership. Her endorsement of Platner is part of their strategy: they're trying to beat as many of Schumer's hand picked candidates as possible, and Mills is a major Schumer ally. Mills is also a really weak candidate (Schumer and the DSCC have really picked some real loser candidates for some very important races because they are staunch Schumer allies) and Platner is a very strong candidate that looks like he's got pretty good odds, especially in a strong Dem election year. I'd also suspect that Warren appreciates that Platner is a little wonky and surprisingly good at the inside-outside game, similar to Warren herself.Warren stans have spent years willfully ignoring that Warren is a snake who wields power pretty ruthlessly and plays politics hard. She made the CFPB happen by being ruthless, she got a seat at the table with the Biden administration by being ruthless, etc. Her image as a smart, well meaning, nerdy wonk who always tries to do things the right way is her marketing. She's definitely smart and wonky, but she's also a pretty skilled hardened political player. For Warren stans who have desperately wanted to ignore that because it tarnishes their image of her, now is maybe a moment to reflect on how much they bought the mythology. Maybe especially how she got them to turn on Sanders.