We can quibble about whether a "hacktivist" group can even exist at all or if it's a convenient lie the Internet has collectively told itself to justify groups of thugs attacking the targets they don't like as "the good ones", but they fit the modern definition of a hacktivist group.
(I remember trying at the time of the incident and having less success than now.)
Thanks for sharing the direct link to that video. At the time of the initial outage, I only saw some assertion that they were 'a hacktivist group' on some article on Bleeping Computer, and at the same time the only reason they'd claimed for the DDoS was 'because we could'. Hacking something just because you can is, of course, not doing hacktivism.
If these people are sincere, they are idiots in their propaganda strategy and artless in their 'hacktivism'... but definitely hacktivists.
But tbh this seems too stupid and ill-directed to me to be anything other than a false flag operation. ¯\_(ツ)_/¯
Either way, thanks for the additional context!