Masking widespread made them feel like they're a majority. They were after all, willing to burn 'my body my choice' at the stake, to politicize them and make them a defacto uniform.
When they see a masked person today, they know that there is a 90 plus percent chance that the person wearing it, is a DUmmy or a modern leftist loon. They think making kids wear masks will convert those kids likewise.
Their pissyness over losing this power play, is the same pissyness they display every time another lefty power play goes down in flames.