I'm going to assume (big assumption here please feel free to fire back on me if you do not agree). This has nothing todo with smash bros being released. This is because it's been fully leaked already and those sources (who are brave/stupid enough) to have ran it apparently are running it under 6.2 since (homebrew is impossible on that version rn).
So the tl;dr to this is: This update sucks, nintendo's becoming apple in it that they are now preventing jailbreaking through exploit patching, not that it's going to help anything since the community already has majority of switches on 5.1.0 with unburnt fuses so... yeah... this isn't even going to help stop people from pirating smash (unless they are looking for online play too).
My opinion on the matter however is I'm a little upset, I'm not saying what they are doing is illegal rather, if this is a active measure against pirating then you should still be able to boot into homebrew, rather this is an attack on all of homebrew. It's like apple with Cydia, people are stealing paid apps, just attack all of jailbreak scene then, close the exploit doors and you close the environment. Im upset that people can't have nice things/they try to prevent nice things.