MLBN is just not on a whole lot of households. I think this is all about NBC wanting the rights to as many pieces of All Star weekend as they can and MLB wanting money rather than exposure.
They should have drawn a line to say the entire first and probably second rounds would be televised and if you don't have a widely available channel to do that (i.e. ESPN or FS1) then you simply are not getting the rights. They know a broadcast network (i.e. NBC) could never devote enough time to this also.
As I said - a misfire by MLB. Lots of people I know were pretty pissed about the Peacock weekend they did last week too. MLB gets a little money. And a few million fans expecting to see their local team suddenly can't. We know this ends in MLB.TV being a true national package when all this is renegotiated, but that does not excuse small misfires along the way.