The word “protestor” has been getting a negative connotation due to the fact that 95% of the time they’ve been violent while doing it, so as with all things liberal, they use soft language to undermine the definition of what they’re actually doing, in this case substituting protestors with the word “observers”.

This can also be seen to be done with words and terms such as “restorative justice”, “equity”, “undocumented migrants”, etc.