How so?
The point on etiquette is that while according to old rules, you're not supposed to refer to former Presidents as President, it's done often enough that it's not a strong argument against Trump.
There would be a Catch-22 at using the argument that it's okay to impeach Trump because he views himself as President, in that it's impossible to do without validating his stated belief that he should have won the election.
The main legal arguments would still be that it's okay to impeach a former official (it was done with Ulysses S Grant's Secretary of War, after the guy retired) and that Senators should view the earlier vote about whether it's okay to impeach as one that settled the question. 55 Senators said it's okay to impeach, so it's okay to impeach. The thing that matters going forward is whether Trump incited an insurrection.
There are two different arguments.
One is that people accused of crimes in other jurisdictions, especially anything political, should be afforded the same level of grace. This fits in with the existing bail reform movement.
The other argument is that bail conditions should penalize someone you don't like.
These two views are largely incompatible.
Goebbels said that Jews were human in the way that fleas were animals, and that both Jews and fleas should be made harmless the same way.
Robert Welch, the founder of the John Birch society, called President Eisenhower a “dedicated, conscious agent of the Communist conspiracy.”
McCarthy claimed to have a list of 205 communists who worked in the state department. No such list existed.
Pravda was notorious for making up statistics.
Their worst statements were not mere technicalities.