[Mick]

I always thought that the "crown" of one's head meant that part which would be covered by a literal crown.  Which would include that portion of the UCLA player's helmet that connected with Owusu.

Here's the NFL rule, Article 8 (g) which separately identifies the "crown" and "hairline" portions of the helmet.  Each are equally illegal:

There shall be no unnecessary roughness. This shall include, but will not be limited to: (g) If a player uses any part of his helmet (including the top/crown and forehead/”hairline” parts) or
facemask to butt, spear, or ram an opponent violently or unnecessarily.

[Mick]

I always thought that the "crown" of one's head meant that part which would be covered by a literal crown.  Which would include that portion of the UCLA player's helmet that connected with Owusu.

Here's the NFL rule, Article 8 (g) which separately identifies the "crown" and "hairline" portions of the helmet.  Each are equally illegal:

There shall be no unnecessary roughness. This shall include, but will not be limited to: (g) If a player uses any part of his helmet (including the top/crown and forehead/”hairline” parts) or
facemask to butt, spear, or ram an opponent violently or unnecessarily.