After consulting with various Endocrinologists SRS Surgeons, and from what I've researched, IMHO the answer to your question would be YES.
Spiro is usually given at the same time as E. Some Endos, prefer not to though, and go the E only route for starters. Spiro reduces T production by various glands... it also competes with T for the same cellular receptors... which in lay terms means, Spiro will reduce the effects T has on your body. It also can cause some breast tissue growth, which is one of the more desirable side effects. So for MTF HRT this is a good thing. See my other thread in this forum for more info.
🙂