K.S.
Don't take the gate down, they are a safety network. I would not give him the run of the house either, you don't know what he is doing if you are down and he is up. If there is a potty down, then keep him down, when you go up, he will go up. A 21/2 yr old should be within eye/ear site all of the time. When he decides he is very focused on wanting to get past, I bet he will climb over.