Burrrr, so I did get it to work as desired with the BAT-to-EXE converter posted earlier by @hermine.potter. Now the command console does not appear just before AM loads. AM launches fine. I checked to make sure that focus wasn't stolen after launching a few games. Seems to be all good and accomplishes what I set out to do. Should be noted that I can set InstantSheller to shell to the exe I created, or works by making the registry change manually.
But but but but, adding in this entry to the registry didn't work for me at all:
C:\Attract Mode\attract.exe -c C:\Attract Mode
Wasn't from a lack of trying either. Trying from normal Windows Explorer after undoing changes from InstantSheller didn't work. Tried it without the 'C:\Attract Mode' suffix at the end of the entry, and with it. With the backslash at the end and without it. With quotations, without them. Made the changes after using InstantSheller and bringing up regedit. Typed in the entry precisely, copied the directory and exe file name from the properties menu and explorer bar even. Nothing worked with this entry. Not very fun doing this on a CGA 15khz arcade monitor, I might add.
Perhaps my installation of Windows for this build has been flumoxed with enough where this would not work any longer. So I'll save investigating getting shelling to work using that registry entry for the next build which will be sometime next week.