I find Squidbagging after splatting an opponent to be a sign of immaturity, and overall bad sportsmanship. It doesn't make me angry enough to block anyone for it, which obviously some people will do, but for the most part I just roll my eyes, or maybe say "really?" to my screen before I move on. All things considered, they're just wasting their own time when they could be getting more of their own ink down.
When turning into a squid then back to a kid repeatedly after winning Salmon Run, or when "partying" in the middle of Turf Wars, I just call it squid dancing-- or squidancing, if you will ;P -- instead of squidbagging to differentiate between that and taunts. It's done with entirely different intentions, after all.