Not a contradiction; according to most poskim (R’ Moshe excepted) we don’t follow this R’ma.
I don’t see how you can be mechalek between the tzorech in 253 and what the R’ma was mattir in 276. I’m not committed to using “midi d’achilah” as the chiluk (v’tzorich iyun), but I don’t believe anyone would be mattir bishul gamur other than for a choleh.