How is Biden's undeniable and obvious severe mental decline different than if he were a doctor with less lives potentially on the line?

Say you had surgery scheduled, and for some reason you could eat right before surgery. You go out for lunch before you're going to be put under that afternoon. By sheer coincidence, the head surgeon is eating at the same restaurant two tables down, and he acts exactly how Biden did.

Obviously if you value your life, you cancel the procedure, right? I mean... that goes without saying, and it's not the question. The question is... What makes the situation with Biden different? Like... I know Trump is bad and I agree, but...

Nixon once said "I can go into my office and pick up the telephone and in 25 minutes, millions of people will be dead." The Presidency literally comes with the launch codes, and we're being pretty adversarial with a nuclear power at war, as I write this. How is Biden's undeniable and obvious severe mental decline different than if he were a doctor with less lives potentially on the line?