It's not that you merely offered an opinion. It's that ...
1. You expressed 100 percent certainty that he would never play a down for the Cowboys and that he would never recover from drop foot,
2. You basically questioned the motive of the doctor who performed the surgery
3. You - not being a doctor yourself - seem to know more about Smith's condition than the doctor who performed the surgery and
4. Having been called out by a majority of the posters in this thread, you didn't take the graceful way out but, instead, remained obstinate to the end.
I think if you had simply said, "I don't think he's going to come back," you might have gotten your typical criticism from the Pollyannas among us. But I don't think it would have been nearly as resounding as it has been.
Just my two cents. And it may only be worth two cents.