The firm's suggestion was "comply or be at serious risk" Because it adds a ton of filing overhead, it seems to be the most beneficial option for them. That's why I thought to post here.
I'll reach out to you directly, if you are available to discuss this further.
I have done this type of structure MANY times, for humans and for payment processing.
EDIT: also, I completely missed your reference to State taxation, and when SaaS stuff is taxable/not taxable. Yeah. State taxation is painful, because the tax is low but the pain for screwing it up is high. On the other hand, the rules are arbitrary and unpredictable, so you have that going for you.