(i) Not a ton of cross-over between Detroit Lions and BYU Cougars, particularly in comparison to LA and BYU;
(ii) Puka was playing for the Rams so a past player drives interest among fans not otherwise inclined to cheer for an LA team;
(iii) Recent history of BYU players and the Lions has not been particularly positive (J-Swagg breaks TD records with Lions and is not even re-signed, KVN played for Lions but was really under-utilized and then goes to NE where he kills it as a patriot; Ansah was an exception as he had a solid run with the Lions before injuries derailed things).

So I don't really see why CB more generally would have any rooting interest that favors Detroit, other than rooting for a perpetual playoff game underdog. That's not much when going up against a West Coast team with a record breaking former BYU receiver.