When it comes to split-streaming, a recording on or second transmission from the model's PC would be almost indistinguishable from the one Streamate is claiming ownership to, except for some potential loss of quality on either side. I haven't heard of a case quite like this being tried in any court, so unless the lawyer in question here is an expert in this subject (and even then), it's probably not something they're qualified to be making particularly confident statements on. As stated, it's a legal "opinion" only. Streamate considers it "official" that it's against their terms. There would have to be a lawsuit to solve the issue.
But either way, we've established that Streamate doesn't allow it. Contract or no contract, they can boot us for any reason, or no reason at all (besides the few protected by law, which protect us even less, since we are not employees). So it's pretty moot--they'll kick a model for split-streaming if they feel like it. The only reason the wording in the contract would really matter would be to determine if they were entitled to withhold earnings, etc. They are under no obligation to allow anyone to use their platform. So why is this even an argument... are we all on the same page now? It's a no-no.
Go ahead and ask them, if you think we're bullshitting you, but we've already told you what their answer is. Geez, even if it *was* only a position of "certain administrators", isn't it clear that enough of them believe it's against the rules that split-streaming should be avoided, given that there's little recourse for any model they choose to suspend?