I finally cracked my problem with the Enterprise plot breakdown
It was a matter of reconciling inner and outer conflict, as
recommended in all the best screenwriting books.
Only once T’pol is able to come to terms with the fact that she’s
metaphorically gay can she work out how to destroy the monster
that sucks peoples’ brains out through their eyeballs. Then her
mum shoots it.
I feel much better now that’s sorted.