If they dismiss they need to acquit and condemn the House at the same time. I suspect Mitch is protecting Graham, Biden, Romney and who knows how many others.
I think you are on to something! I am willing to bet you are spot on!
The Senate sure needs to Acquit. Acquittal seems to matter most, and will advantage POTUS, going forward, according to Trey Gowdy.
I believe a dismissal without acquittal will fail to condemn the false charges and the political assassination tactics of the Schiff House Committee in order to push those charges into Articles of Impeachment.
Acquittal seems to defend Trump, whereas dismissal alone seems to me to
leave “innocence” in question or undecided. Just musing, here.