> Is there some inherent human right against persecution?

"Human rights" are a social construct, there's nothing inherent about them. Regardless - Assange was under no obligation towards Sweden given the circumstances.

> Is it "fair" for me to avoid questioning (or consequences of questioning) about crimes of which I'm accused, too?

1. Assange was not charged with any crimes.

2. Assange did not avoid questioning - neither in Sweden nor in Ecuador (= Ecuadorian Embassy). He only avoided exposing himself to US-instigated persecution.

Accused. In intimate crimes, where the only witnesses are the accuser and accused, it is typically extremely rare to charge the accused absent any interview whatsoever, so the "he wasn't charged" doesn't change my point.