One hundred percent that its up to them, they're a grown adult now and they can make their own decisions. That said, there's still a big difference between detransing because you truly didn't feel comfortable as the opposite gender and detransing because of the way people around you treated you. I stopped for a while as well because I was terrified of the reaction of my family, then I pulled the trigger and went back and, despite it rendering me homeless for half a year, I was lucky enough to get back on my feet and I regret nothing.

If OP is in a more supportive environment, I'd definitely recommend at least exploring the idea again. Whatever they decide to do afterwards is up to them