"Can you tell me more about the fork weakening? I don't want to do something to my bike that makes it more dangerous."

Threaded forks are thicker than threadless forks so that when metal is removed to make the threads, the fork is still adequately strong.

If you start with a thinner threadless fork, and then remove metal, you compromise the strength of the fork.

It's a pretty silly move when you can buy a new threaded fork online for less than $100, and keep your threadless fork as a backup.