"if Corbyn said anything close to what Johnson has"
Corbyn has done way, way worse in my opinion (and clearly the public's, given the respective popularity ratings of the two leaders). But I am guessing you don't find taking money to be a useful idiot on Iranian TV, or praising any anti-Western dictator you could name, or describing Hamas as "friends" all that bad.
The guy has an absolute fetish for any dictator or horrible regime as long as it's sufficiently anti-Western.
But right, Boris told some off-colour jokes and was a bit rude about people.