No, not actually saying Trump will pick the Senator, but a political move, of course.
Trump can support, or withdraw support on Moore, and it puts him in a bit of a no-win situation.
Does he stand by him, and have all his critics say "No surprise from the man who said grab'em by the p***y".
Or, does he not support him and have his critics say "See, he's not interested in draining the swamp, he's one of them".
The best thing Trump can do is say "This is up to the people of Alabama to decide", and leave it alone.
McConnell is counting on him not doing that.
The history of Trump and his tweets show that McConnell is probably right, in this regard.