Yeah that's not what doorsitting means in farms. Doorsitting in a farm has a distinct definition. What you described isn't it. Anyone who actually farms with any regularity knows this. It's literally sitting at the door doing nothing while the farmer or farming team clears the map. It's NOT bringing along lowbies on a radio mission.
And farmers will literally announce in LFG: Farm forming looking for doorsitters, or Farm forming for lowbies. PST if you are looking for a boost.
EDIT2: A little boost to control and support is fine. Though again I think Doms, Defenders, Controllers, Corrupters, do just fine while using their secondary and primary on fast moving teams. They are always welcome on TFs, especially where there are hard targets like AVs.
Fast moving trash missions I couldn't care less about. It's a radio mission, there are no stakes there unlike a TF which is a time commitment that you don't want to fail.