Whitehouse.gov presser by Pence, and others he's made, say " Wear a mask if you’re not able to practice social distancing, or wear a mask if state and local authorities direct you to do so in the situation that you’re in."
In my humble opinion, this shift seems to discourage protests specifically against masks where the State or local government requires the wearing of masks. I would say this is likely strategic - Trump et. al. knew what was going on at protest sites before the public knew, and I would say it's possible they know there is some plan on the part of the State/local police to use masks as an excuse to "crack down" on decent people. So while there are ways to resist, it looks like refusing to wear a mask in public where it is required by local government is not something they want to have happen at this time.