In and of itself, it's a crime. Biden should have had classified material when he wasn't in office. I hope they do take him out for a walk on this because this shouldn't happen. Whomever/whatever security apparatus we have in place needs to be drastically overhauled if classified material can be missing for years and nobody know where it is. One would think this stuff should be audited more aggressively.
As for the politics of it...the right wingers blew their load on Trump (as they always do) and it's funny watching them try to gin up some scandal when their blob committed a much more egregious crime of the same nature and fought to keep top secret documents even after they were discovered missing.