Exactly. But if the evidence is plastered all over the internet and on the front pages of newspapers all over the country after its release into the public domain by a House committee, then there's no "wrong way" for the information to be introduced.
It's surely no coincidence that Flynn's sentencing was delayed this week -- under an request signed by both sides.
As for the argument based on Strozk being biased against Flynn ...
"Bias" is the least of Strozk's problems. We're talking about criminal conduct ... by a member of the investigating team ... during the course of the investigation.
I don't see how a charge of lying to the FBI can possibly hold up when there's credible evidence that the FBI agent who was allegedly misled by Flynn was fabricating evidence against him.
And here's something else to consider ...
In common law, there's something known as the "Entire Controversy Doctrine" that requires the parties in a legal dispute to adjudicate any and all charges (in a criminal case) or claims (in a civil case) at the same time. So (for example) if I sue you over a motor vehicle accident that occurred last month, and my dog bit you six months ago and you weren't sure about suing me at all, you will forever forfeit your right to sue me later over the dog bite if you do NOT file a counter-claim now in my lawsuit related to the car crash.
Under this common law principle, Mike Flynn would have the right -- even the legal obligation, if only to protect his rights for legal redress -- to file civil claims against Strozk, the FBI, and maybe even Mueller himself (even if just as a formality) on the basis of the evidence that emerges from this HPSCI memo.
If nothing else, it gives Flynn's legal team (along with anyone else who is facing charges from Mueller) the right to subpoena any and all persons and organizations named in the memo. Mueller may be forced to drop each and every charge he's filed or is even considering filing -- just to avoid a catastrophic scenario like this.
As for the Nunes memo having any play in the Flynn prosecution, the fact that something is all over the news does not bring it into the case. Mueller controls the evidence on his side, and is obliged to turn over everything he has that is exculpatory. Bias on the part of the investigator is relevant, but has not been disclosed to Flynn in the context of this case. The news is "outside" until the prosecutor or defendant brings it in.
Charging Flynn might be fought off as an abuse of prosecutorial discretion. Same conduct seen by the same investigator (Strozk) in Mills and Abedin, no charge.
At any rate, I think the delay is because Mueller does not want to put exculpatory evidence in a place the public can get its hands on it. Just that simple. Flynn doesn't mind waiting. Not that waiting isn't a burden compared with being exonerated, but preferable to being sentenced.
All the rest of this stuff plays out in the court of public opinion, which has an entirely different calculus.