
Evidently this Rabbi Yehoshua Heschel ben Avraham of Shklov was a Shas Pollack (מפורסם בשמו בשם ש"ס פאלק). Judging by the description ("great rabbi" "expert in Shas, Posekim and the whole Torah") he was far from marginal or a חמור נושא ספרים (link).
Actually, I have a suspicion that this isn't saying he was a Shas Pollack (pin-test guy) at all. Falk (פאלק) is a Yiddish nickname for Yehoshua, and given that he lived in Frankfurt but was from Poland and such an accomplished talmid chochom perhaps his nickname was ש"ס פאלק, a sort of pun.