Totally, I understand that realistically they are in the power position. Like I said I make no efforts to throw nonsense into the chat hits, I just usually run multiple at a time to account for downtime between their responses, fills the void of staring there at the unchanging screen. All I can say is that nothing has been said to me personally and I continue to be eligible for Noah hits. If a block were issued would it result in an email like receiving quals sometimes does?
Yes it would come as an email, through the Mturk messaging system. I don't think multitabbing would be an issue. Not my call but, I know that when multitabbing, if a requester has an issue, one of these phrases "No distractions, Don't switch out of this window, You may only have one instance...etc" is usually on there. That said, I guess no requesters would put that there until they have a problem with it the first time. Then they'd reject or approve and implicitly say it. Then they'll say that you weren't giving it your full attention, therefore not providing quality data.(whether or not I agree with this is moot)
On the other note, once you try to select your partner, removing the randomness, you're definitely getting to the point where data starts to get skewed. Since you'd know your partner, you'd have info(from previous chats) that you shouldn't have about their likes, have established rapport, etc.
This is just my experienced opinion. It's your turk account, you have the right to run it how you'd like and everyone has a different risk tolerance.
TL/DR Yes. An email.