But it’s not like Rumple, Hook and Bae ARE those ages. Rumple is not 300 years old, when the Dark One’s Curse leaves him he won’t age several hundred years. They were all just frozen at their respective ages for a long time. Rumple has been around for 300 years but he’s still about 45-50yrs old. The same with Hook and Neal. Hook is only about 30-ish but he was frozen for a long time. Neal is about 36-ish but he was frozen at the age of 14 for a long time.
Also, not to put too fine a point on this, but these are fairy tales where stuff like this is just part of the genre. In the real world, huge age differences are frowned upon but in fairy tales where often times people are cursed to not age this is just part of the trope.