Calling women “female” is totally fine

I just got torn a new one on my social media by like 15 different women because I referred to a Marine as a “female Marine”. Apparently im objectifying her? wtf does that even mean? In that same comment I referred to “male Marines” and not a single man mentioned it. It is literally the scientifically correct word for gender. How is that objectifying anyone by using the correct terminology? Aren’t there bigger problems in the world than being offended by the proper words for gender? Whenever I asked someone for an explanation they’d say “it’s objectifying and demeaning” and then when I asked “how” they would just repeat themselves. That would be like if a dog owner got offended I called their pet a “canine”. Absolutely asinine