Blockchains (due to constantly changing validators, nodes, etc.) are much harder to shut down than some dedicated service. I think the current administration understands that loose stablecoin regulation further cements US dollar hegemony, curtails other countries attempts to deprive their citizens of payment and savings alternatives and creates more demand for US treasuries (because that's where stablecoin reserves end up). It's a win-win for the US government and bad for governments with a track record of poor fiscal and monetary policy.