It kind of makes using him as a witness against anyone else really hard. He has plead to lying to the FBI, which any decent defense attorney will bring up ad nauseum in a cross examination.
Not to interfere with your stupidity, but consider this:
Prosecutors work it this way......"Tell me all that you know BEFORE I hand to you a sweet plea deal"....................and NOT, "I'll give you a sweet plea deal.....and maybe you'll tell me what you want to say....or maybe not."
See the difference?
Let me help you out, junior, if there is a crime that prosecutors are trying to pin on the big guy, the plea dealing criminal will have that plea deal set up in such a way that the underlying crime, that would allow them to go after the big guy, is actually NAMED in the plea deal.
See anything like that with trump?
No? Is mueller the stupidist prosecutor the world has ever seen, or is there no other crime?