i'm hella late commenting, but painting over legal street mural is so 2003. old news.
writers who choose to paint over that shit, be it tight or not, are sending a message to those "artist" who want to paint legal shit, that you're fucking with my medium now and thats how we roll. if its some gay ass mural in a prime spot its eventually gonna get taken out.
temporary is the nature of the art. theres no rules to this shit. it fucking what ever you want it to be.