interesting question
the charges against Samourai appear to rest mostly on a conspiracy to assist in laundering proceeds of crime. as this is already addressed in the laws, not strictly regulation or an interpretation of laws, I suspect the new Chevron decision will not play a role.
now, as for the promulgation of new regulations, like the FinCRN's NPRM related to mixers, etc., that was going around in late 23 for comment... that's the sort of thing that might get rekt (legal term) if it was actually released/published/made official.
NB: as of now it is still in PROPOSED status afaik. (I'm not a lawyer nor am I offering legal advice.)
https://www.fincen.gov/news/news-releases/fincen-proposes-new-regulation-enhance-transparency-convertible-virtual-currency