In other words, you want to ensure that any company large enough to pay software developers to write patches for open source projects will never submit a patch to your open source project.
So you're idea is to hope that some large company hires an FTE to contribute to your project full time? Sounds like a very poor bet.
Anyway, I would vastly rather they pay me to write the patch properly, the way I want it, the way I would have designed it. Much easier to maintain than than a drive-by patch.
As long as you are paid regular enterprise-software range fees, hiring your own freelancers to help you write patches is also easily achievable.