Do you think Trump should be able to have his DOJ and friendly courts imprison Joe Biden for his administrations criminal negligence at the border? (As an example)
There are plenty of things the Biden admin has done that are far less of a stretch to get to criminality than making a constitutional argument about electors.
Of course Trump should not be able to imprison Joe Biden unless Joe Biden broke the law and was found guilty of breaking the law by a jury.
However, with this ruling, now both actions are codified as being able to take place legally and lawfully as long as deemed an official decision. Not even via jury decision but by direct action from the executive at the behest of the judicial branch. So, if Joe Biden is in fact targeting political rivals, now it's fully with in his power to do so if deemed official.
And this applies both now and to every future President.
You merely celebrate it because as Trump supporter, it potentially absconds him from criminal proceedings involving his recorded phone calls to the Georgia prosecutor to "find votes". Essentially, any potential action for accountability is rolled into executive privilege (all because Donald Trump could potentially be found guilty by a jury of peers). No one should celebrate this and the only reason it is celebrated is because it may help the Trump campaign.