Masked protesters outlawed (sort of)

Protesters in Washington, D.C. are now required to notify police prior to protesting outside of private residences while wearing masks.
Failure to do so "may" result in arrest.
A large part of the reason for this "strongly worded" bill is to curb animal rights protesters who have been harassing and intimidating people at their residences.

I don't understand why anyone has the "right" to wear a mask while protesting.
You absolutely do not have an expectation of privacy while engaging in such public arguments.
Anyone familiar with human nature knows that facing masked strangers who outnumber you and are (usually) in the grip of high emotion is intimidating and that wearing a mask provides an illusion of power that may lead some to commit acts they would avoid if they were exposed.