Actually, she does watch and rather closely. She's been criticized in the past for comments regarding other offensive players, specifically when the team lost in large part because of receiver drops.
I agree that the refs seem to treat him with kid gloves, but he has been hit and he's not 26 years old anymore.
Moreover, as a top model used to traveling the world and enjoying a certain lifestyle, I'm not shocked that she's speaking out about this now. She's not uneducated on this. She's been around football and football players enough (even if only in the context of entertaining and watching games) that she's worried about the active health of her husband.
Which is totally reasonable. Between the two of them, they've got a huge mansion and enough disposable wealth to live the life of Riley and have their kids and beyond never have to worry about a thing. I can't imagine that she would want their lifestyle disrupted by Tom's football injuries stopping their activities (Joe Montana's revelations as to his activity restrictions was kinda eye opening). Not to mention the potential for ALS, CTE or other neurological impairments that are deadly.
Sorry to be the ice bucket, but I tend to believe when people are serious about serious things.
It wouldn't surprise me at all if Giselle wanted Tom to retire after they won the Super Bowl. They have everything they could possibly want. She wants an active, healthy husband for a long time. What wife doesn't want that?