The main problem I have with the article is that it's factually incorrect about it being easy to spoof an ip address in a situation like this. It's easy to send off a fake ip address if [1] your ISP permits spoofed ips (which it shouldn't) and [2] you don't care about a response. But in this case the user had to actually log into the system, which is pretty tricky to do with ip spoofing. (There is some debate about it potentially just requiring an email to be sent to a mailing list, but even SMTP requires various responses).
Given the level of technical difficulty to do this, it seems extremely implausible that someone would go to all that effort just to send out this message.