Well, that could be bad... but,.. it might not be...
It may have just gotten overheated enough to cook that oil that had leaked from the head plug,... and the poor starting/running caused by an unrelated issue of stale gas...(usually, an idling engine that overheats will just die before seizing)...
Give it a fresh oil change,... drain the tank, and carb float bowl,.. and put fresh gas in it...
Then, see what you got...

...
JMHO,.. that's what I'd do ...