Your assessment is correct that they are approaching you at your lowest. You said it yourself, albeit in different terms: they're trying to take advantage of you. This is a good sign that they're at least somewhat threatened by you and want to make you complacent.
It's not clear from your question what they've offered in terms of how many clients you'll get or how they'll decide that, but I'd imagine if you took the deal it would somehow work out that you got very few clients, those clients would be low quality, and you'd have a big loss in autonomy. When you give away parts of your company, you want to do it because you can see them giving you more than that back in value, not because it could help you barely scrape along (which is what it sounds like you're looking at with this deal).