That might be one of the concern, but the TOS clearly doesn’t state that. They only prohibit against attaching multiple devices to the network. If you attach it to your desktop PC, it could be considered not on the network as long as you don’t bridge the two connections together.
Oh yeah, they did mention that clause. I guess you can still limit the power of the wireless router so it doesn’t penetrate too far outside the rooms, as well as using bands that is not as congrsted. That might be good enough to comply to the TOS, or it might not.