I can understand that we might want to avoid the obsessive behaviors of some developers that could be considered unhealthy, but blaming a simple catch-phrase isn't going to get us anywhere.
What if the shirt said, "Coding is rad" ?
I say that all the time, and people just give me that look that says, "Ha, what a nerd" and it's fine for me because I can maintain my enthusiasm. Other people need a little bit more of a push to continue to push themselves to be the best developers that they can be.
Should developers be monks that only exist to program? No. Should developers take pride in spending their time learning and improving? Yes. Should developers be upset over a t-shirt that has no impact whatsoever on their life? No.
I hate this sort of reactionary outrage, it's more counterproductive than buying the stupid shirt is.