Many people had concerns about Vindman including Fiona Hill, so much so Hill briefed Morrison about his judgement and the possibility that he was leaking information. This isn’t a “Republican talking point” it was a general consensus. #ImpeachingHearings 
“Hill and her deputy and others in the office about Alex’s judgment..so (Morrison) wanted time mange his involvement carefully. #ImpeachingHearings
Worth noting, no one in on the committees or the witness himself are questioning Vindam’s service, rather perhaps hes not suited for said position.
This really seems to be the heart of the issue Vindman was concerned he would be viewed as “not relevant” this game to light when Morrison consciously excluded him from trip, he was pissed enough that Morrison wanted a witness.
