I guess this is a big topic that a lot of people are confused about so I will clarify.
It is
NOT Server Disruption for a Traitor to be opening up the T room for innocents to enter and I will explain below:
looking at the core gameplay rules of TTT the role Traitor is defined as:
This is viewed as a strategy for Traitors to employ to win the round. Keep in mind that just because the traitor room is open
doesn't mean an innocent is forced to enter it and is a decision they make themselves and should be aware of the precautions before entering. (Innocents can be
killed for entering the room as it is considered Traitorous behavior entering/leaving a traitor only area)
Now I am going to disagree with making it server disruption for innocents to enter the room because there are numerous amount of reasons for innocents to enter the room (trying to kill traitor, ID bodies, etc). Also as for camping innocents should be actively pursuing the round not camping as it is considered server disruption as it is just delaying the round.
TLDR not server disruption just a strategy. (love/hate it)
This question was asked a long time ago
here if you would like more info on the topic as well.