I haven’t looked at 1e in a long, long time. But I’m assuming a 1st level wizard couldn’t cast all those spells, even if they had them in a spell book. So I don’t see it being a problem at all. At best, they would just have easier access as they level, instead of having to search and/or buy the spells to record in their book.
In fact, if the DM wanted, it could be the opposite of empowering. This puny little 1st level wizard now has a trove (that they can’t use) that a whole lot of higher level wizards would likely kill for. Plot hooks galore.
Also (again, my 1e knowledge is rusty), didn’t wizards have to scribe spells into their own book before gaining access to them? So, just having them available for scribing, doesn’t necessarily give them automatic access to the,. They still need to make the Learn Spell roll, right?
Again, apologies if my rule knowledge is wrong. I have too many editions in my head. But I don’t see it being a problem, and in fact could generate an awesome amount of stories for the group.