Insurrection is against the law. It is 18 U.S. Code § 2383. You said correctly in reference to the BLM riots that courts had a definition for what was insurrection, and again correctly the courts had not decided the BLM riots were an insurrection. The courts have also not decided January 6th was an insurrection.
If you want to see what the slippery slope looks like, it looks like you. First you started with a claim that Trump should get no due process because the Constitutional clause regarding insurrection was self executing, to then falsely claiming insurrection had already been decided by the court, to now holding to the candidate you don't like shouldn't be allowed on a ballot because people who were not the candidate were convicted of crimes that were not the crime cited in the Constitutional clause. You aren't even playing 6-degrees of Kevin Bacon because your pieces don't connect at all.
There is a candidate you don't like and you are working backwards to erase him from the ballot using any means. If you had the governmental power to do as you've indicated using what is apparent to everyone as clearly not applicable and without precedent, do you really think there is no counterpart to you on the politically opposite side of the divide who may someday be in the position to use your methods to remove candidates they don't like? Do you really think that only operators sharing your political beliefs would play hardball like that?