What sectarianism would that be?
Fans of opposing clubs will snipe at each other, it's how football culture works. If this was a mixed forum of Everton and Liverpool fans they would be arguing with each other, but no one would call it sectarianism.
Sectarianism tends to be people being against a religion, or sect. I accept Scotland is still a bit anti-Catholic, but some people label every footballing discussion as sectarian, which isn't correct.
I'm pretty sure no one has prevented Brian from posting his views on Scottish football. Perhaps if he, and others, posted more there would be less focus on any arguing between Celtic v TRIFC supporters, or sectarianism as some people have labelled it?