Of course the ONLY reason to not release the transcripts is because they would show they are lying. If they exonerated him they would have been released already.
I would like to add that I strongly suspect that this whole business of digging up dirt on Biden is a smokescreen. As corrupt as blackmailing a foreign leader into attacking a political rival is, it doesn’t rise to the level of being an “urgent” threat. If that is the totality of the whistleblower’s complaint, that cat is already out of the bag. So why not release the transcript?
This is a shiny object-red herring designed to draw attention away from much worse acts. We should not fall for it. Until Adam Schiff and the The House Permanent Select Committee on Intelligence is allowed to see the full complaint we wont know what the real threat is.