My argument is that Father Time (i.e. skill sets degrading as we get older) combined with an increased amount of hits will shorten his career. And it's literally backed up by the entire history of NFL RBs. And it isn't just helping him lengthen his career that I'm worried about. The more a player gets hit, they higher chance they have of getting injured. And the more hits they take, the higher toll it takes on their body in general. Hits add up, even to freaks like Henry. I would prefer him to not take unnecessary hits and risk losing him for the postseason, or risk his effectiveness going down in the post-season.
Your argument is "Well Tom Brady is able to play at high level at age 44, so you are wrong!" And there couldn't be a worse argument made.
Not only does Tom Brady play a different position, but the reason he can still play at age 44 because he has managed to stay healthy. Part of that is luck. Part of it probably good health management on his part. But the most important aspect for him staying healthy has been avoiding hits. Because you know the number 1 cause of QBs not being healthy? Getting hit.