am under the impression either Aquinas or Assisi was pretty much agnostic on the subject.
What gave you that impression? Something you read by St. Thomas or St. Francis?
There has been a question of when ensoulment of the baby in the womb occurs. This is not the same as validating abortion even prior to the putative ensoulment.
Certainly either saint is entitled to their opinion; that wouldn’t make it the opinion of the Church. However, I would like to know what is the source of your impression.