Correct. They wanted a GE when May (who was electoral poison) was in charge - or after No Deal to exploit any difficulties that arose. They're terrified of one now against Boris (whose personal popularity ratings are surging).
Problem is, no Leader of the Opposition can reject the chance of an election and hope to retain any credibility - let alone be able to get away with wibbling a load of old balls about 'coups' and 'An unelected Prime Minister' (don't get me started on that, btw).
Mind you, it's questionable how much credibility Corbyn still has to lose.