Any arguments that their plans to monetise aren't public are not credible. Plans are public and benign to the interest of the stakeholders. Known shills in this thread claim otherwise when it has been explained to them already.
Any arguments that suggest this centralises the dev team further are not credible. It's centralised now, it was centralised before, and it will be centralised under any other management. That's how the development process works.
However, any arguments that Blockstream are deficient in their design ideas are those that I am willing to entertain. I'm not as familiar with their proposal as I could be, still haven't read it in full. But if Blockstream ever appear to be against the spirit of Bitcoin, I will not favour their solution, or anything that promotes it.
Superficially at least, Blockstream satisfies that basic stipulation; Blockstream's proposals thus far only enhance Bitcoin. We will have wait to see if that's what materialises.