Exactly what it says on the tin. Instead of cursing Mary Lou, Tina simply works a non disruptive spell that ends up revealing Credence is a wizard.

And sure, he might be only ten years younger than her at max, but he definitely missed out his childhood and Tina just wants to mother him a bit. Cue Credence finding a loving family and never having to repress his magic anymore.

Grindelgraves is legit horrified.