Attacking the source, or an “ad hominem” attack is one of the logical fallacies. However, saying that someone is a “bad person” may be irrelevant as to whether their argument is valid or not, it is not a logical fallacy to judge the trustworthiness of testimony based on the character of the person giving testimony.
I served in Europe just a few short years after the incident outlined in the link took place. I’ve actually trained in the facility mentioned (although not with the Russians as they’d done the Crimean land grab at that point). https://www.thegatewaypundit.com/2019/11/revealing-military-official-who-worked-with-top-schiff-witness-alex-vindman-reprimanded-him-for-inappropriate-and-partisan-behavior-in-military/
While I am not a close acquaintance of LTC Hickman, we did serve in the same theater together during overlapping periods, and I have no reason to question the accuracy of the his recollections about then Major Vindman.
Other military professionals have taken a cursory look at LTC Vindman’s fruit salad (ribbon rack) and come to a few conclusions. https://www.redstate.com/streiff/2019/10/30/dont-need-question-ltc-vindmans-patriotism-lot-questions-ltc-vindman/
If you read LTC Vindman’s testimony, you would know that he revealed nothing new, and provided no evidence of wrongdoing by President Trump. He wears his ribbons out of order of precedence (a punishable offense under the latest revision of AR 670-1), including his parachutist badge and Ranger tab out of order. The only reason to do that is to highlight the purple heart rather than awards for being on staff, and the fact that at one point as a much younger man he earned the ranger tab (like 70% of all Infantry Officers in the US Army, really, it’s not that big of a deal). His unit affiliation is the 2d Cavalry Regiment, a fine outfit to be sure, but not as distinguished as the 75th Ranger Regiment or any of the other “cool guy” units that demonstrate someone has “been there, done that.”
Additionally, the current state of the military blogosphere is oddly quiet with people jumping up to defent LTC Vindman. With a 20 year career, surely there is someone who would know him well enough to rise to his defense if he was truly a man of impeccable moral character.
And maybe he is, maybe he’s not a political animal who plays up a purple heart from a single combat tour to sell himself as a “decorated veteran” to the media. Maybe he’s not a guy who did the minimum time necessary in the Infantry before bailing to be a Foreign Area Officer and spend the rest of his career working out of embassies. But I don’t think so. An Officer of the United States military does not get to say the President is wrong about foreign policy. That didn’t work for Oliver North, and it certainly won’t work for Alex Vindman. Quite literally the sentiment I get from field grade leaders is, “a 20 year career and fewer combat stripes? Where was he hiding out? What the hell was he doing?”
In short, LTCs are expected to haul the water for those who are actually in charge of making policy, not attempt to make policy themselves.