It is bad etiqute to call people out on this via the league message board? Or email the Commish? It's a $150 league, so people should be somewhat invested, right?
To go 3 or 4 days without seeing it could just be because that person only looks at FF on weekends. Or as another poster has stated, he could be looking at other offers. If it went a week, and he updated his lineup, then it's just not responding. I know I have done that in the past, I have a league where I receive regular lowball offers from a certain person for RBs. It's gotten to where I don't even take that person seriously any more and don't bother giving them the time of day when they offer trades. Unresponsive of me? I look at it as not wasting my time.
I don't think it's appropriate to call him out or complain to the commish. The owner is under no obligation to entertain anyone's trade offers. He paid his money just like everyone else, and he should be able to run his team however he wants.