As far as I’m concerned, when you receive an annoying text from an unsolicited number, all social norms and niceties immediately fall to the wayside.
A spam text is an act of war, and people should be permitted to respond accordingly.
If you’re a professional annoying person, you want to make sure your victims won’t be able to turn the tables on you. If you don’t take the proper precaution to stop that from happening, then you shouldn’t be allowed to complain when someone takes advantage of your inability to plan ahead.
The ensuing exchange proves that if you’re going to make a living being the worst kind of person, you should probably invest in a burner phone.
If you don’t do that, then it’s on you to accept the (mildly annoying and ultimately harmless) consequences.