As others have mentioned, this is more or less how it currently works, although application of this will often seem inconsistent for a few reasons.
If innos are in the t room, they can (for the most part) kill indiscriminately. If they're knowingly killing innocents purely because they can, karma will handle most cases, or toxic gameplay can be considered, but it would need to be pretty excessive and proving intention is difficult most of the time. An example of where we might apply toxic gameplay punishments when an inno kills another inno for being in the t room would be if the t room in question had a physical button to open it, and said inno let another player into the t room, then killed them for entering. Even then though, context would be needed to determine if toxic gameplay applied.
As far as how they got into the t room, if innos are let into the t room accidentally then no one is held responsible for those kills in terms of RDM. If innos are intentionally let into the t room by a traitor AND the traitor did not warn their t buddies sufficiently ahead of time, the traitor would be held responsible if it gets their t buddies killed. Notably, if we can't prove that the innos were let into the t room intentionally, or we can't prove that there was no warning provided, we won't slay for it in most cases.
And I think this works out pretty comfortably most of the time. In practice, this should mean that slays are pretty consistently applied when people are intentionally trying to get their t buddies killed by opening the t room, and not when it happens by accident.