I played the violin. I'm thinking about re-teaching myself, but I've never had a problem wioth that issue for the exact same reason you mention: non professional playing. The orchestral setting is the only reason why playing with opposing posture would be discouraged
The hostility probably stems from the structure of violin schools really. They only want to teach you one way-the "ancient" way that's been passed down for centuries. If they can keep the art as structured as possible, they will. Hence people who get really caught up in it are incredibly serious about seeing it done in one way only. That leads to the ostracizing of the people that do that art differently-but achieve the same results.
Also, the people could just be jealous.
My take- screw them, because the internetz is serious buisnezz ¬¬ Play because you wnt to and hell, if you do get in an orchestral setting, make THEM switch. Take the world on!