Avira, thanks for explaining details of how exact you are in your judgment of Talmidei Chachamim. I have to assume that they did some aveira in their life to deserve this din veheshbon in addition to the Big One. Maybe they did not say birkat hamazon with full kavanah, or forgot a blatt before bar mitzva .. As Syag is saying, if you are confronted with T’Ch having an opinion, especially in his area of expertise and you would like to disagree, you could read at least his 3-page article, or maybe 3 200-page books …
Note that R Twersky was asking Steipler Gaon regarding his plans to study medicine, so I would presume he was asking him later also. Steipler passed away when R Twersky was 55, so one could presume that he ran his major ideas by him.