The beauty of learning to play scales HT is that if you can play them HT, you can also play them HS.
Regarding fingering, I see nothing wrong with teaching the traditional scale fingerings first. When learning literature that contains alternate scale fingerings, a talented student will know why those fingerings are suggested, change (perhaps with the help of his/her piano teacher) the fingerings that don't work, adapt & adjust. There are always students who think that because they learn a certain thing a certain way, then it's always
that certain way & that it can't be any other way. That's where the problem lies. Like students who get it into their heads that Middle C must always be played with the thumb, :rolleyes: I imagine that there are also students who think that scales must always be played with a certain fingering. What does a teacher do in a case like that? Teach the scales HT using traditional fingerings, but at the same time assign literature pieces that contain scale passages that may or may not contain traditional fingering. Hopefully, if a student learns scales both in exercise form & through the literature that s/he is studying, s/he will be able to adapt & adjust without major difficulties. A little more practice maybe, but no major anxiety. It's amazing what can be accomplished with sufficient practice.
Lastly, I think that the teacher needs to be careful about the music s/he selects. If the teacher doesn't like the fingerings that are suggested in a certain edition, then the teacher should find another edition with fingerings that s/he likes or use an urtext edition that doesn't have fingerings. If that's not possible, the teacher can always use good old Liquid Paper (White Out) & a trusty pen or pencil to edit the fingerings.