Objection? No. Concerns yes, as have been detailed at length. No good trying to ram it through without doing the work. We can't manage the project for you etc. etc.
There is no silver bullet. You have to treat each one in the way that works for them. Those who do it well, it's a talent.
Or have the compromising photos of the boss and copies of the bank statements so he's scared and backs you publically always and then just roll anyone who isn't effusively enthusiastic. That works too. Wouldn't recommend it.
That's ok. Setup a meeting with said stakeholder, clarify your position, ask for input, and in the end ask straight up if they have any objection. Save the meeting minute and send it to everyone who attended the meeting.
They need to put up or shut up. Playing games does not work.