OK, I see. You wouldn't be glueing the steeerer tubes together, but you'd glue one bit to the stem, then use the stem wedge to lock the top part to the rest of the fork. That might actually be doable w/o being too horribly reckless.
If it was me, I'd splurge on some loctite used for mounting bushings instead, it's made for filling gaps like that. And I'd be really careful about surface prep of the concerned areas. If it's a chrome steel stem I'd grind the chrome off.

And at the end of the day it's still in the category of "doable, but not recommended or worthwhile fixes".