The versionlock.list file does not get backed up, thus not getting restored during the rollback.
Reproducer:

• install yum-plugin-versionlock
  • yum install -y yum-plugin-versionlock
• versionlock at least one of the packages
  • yum versionlock kernel
  • the versionlock is now set in both /etc/yum/pluginconf.d/versionlock.list and (if present) /etc/dnf/plugind/versionlock.list files, which are not empty
• run convert2rhel analysis
  • convert2rhel -y analyze --debug
  • convert2rhel recognizes the versionlock is set (file exist and is not empty)

After the rollback both the versionlock.list files are empty.
Same goes for the /var/lib/convert2rhel/backup/versionlock.list

EDIT: This seems to be only related to EL7 systems/yum.