Accused of "attempt to direct the party towards liberal anarchy and revisionism", he was nonetheless convoked to express criticism of the writers Alexandru Jar, Mihail Davidoglu and Ion Vitner, all of whom had displayed similar support for reform. Constantinescu was purged by the Party Plenum in June 1957; he was marginalized, but kept his freedom and was allowed to work as a lector for the Pedagogic Institute, and later as a researcher for the Romanian Academy's Institute for Economics and the Nicolae Iorga Institute of History in Bucharest (led by Andrei Oțetea at the time). Active in the revival of sociology studies after the Stalinist period, he was notably engaged with Henri H. Stahl on the "Bibliotheca Historica Romaniae" research project.