If this ruling holds up then that would likey be the same for FFS. Which would be a great victory for TS women. An unlikey ally in the Internal Revenue service.
It is not obvious whether the IRS will, or will not, appeal; they have not exhausted all their appeal options.
The thrust of the IRS argument is or was:-
The medical evidence
laid before us says that GID is a disease of the mind to be diagnosed by psychiatrists, not a disease of the body to be diagnosed by internal medicine doctors,
and
genital surgery treats the body, not the mind.
Therefore SRS is not a treatment for GID, but is something else.
Some will accept that argument, others will reject it, but that is their argument.
Some will say the petitioner set forth evidence that GID is mental illness in bad faith and despite a belief that it is not.
Of course, what IRS is really afraid of is that if the principle is established that surgery can be medically necessary as a result of psychiatric diagnosis then that category will expand exponentially to include most surgery that is today regarded as cosmetic.