Why would you say that? McConnell has not tipped his hand yet.
He faces a dilemma. On the one hand, Trump is delivering the flow of judges that McConnell wants and Mitch is savvy enough to see that if he crosses Trump on this, he could lose their connection.
On the other hand, if McConnell allows the bill to pass by a margin that cannot override a veto, he will be known forever as the Majority Leader who surrendered a substantial amount of Congressional power to the Executive Branch, regardless of whether the courts bail out the Congress on this one.
I keep reading McConnell is also worried about a primary challenge in the next cycle, which is a reason to fall in line behind Trump.
I think it best to judge him after he acts, right now all we can see is his dilemma.