Well, a grayshirt (or a maroonshirt, for that matter) isn't really signing the guy in that class, because he either isn't on the team at all in the fall (gray) or he's actually a PWO the first year (maroon).
So that's a bit of semantics.
I don't think that "less than 25 the year prior" is valid. Otherwise, you could have a team sign 15 new counters one year, and you're saying they can sign 35 the next year? I doubt that.
The 25 rule (and it was tweaked I think in 2017 or 2018 to take away some loopholes) was primarily driven by SEC oversignings. In 2009 Ole Miss signed like 37 players? Just silly