Other services used users' computers as exit nodes without clear disclosure. Users found out when services blocked their IP addresses. And why would you assume NordVPN would take any legal heat?

I mean, if this is the case, and their users aren't aware. If the users are aware, and want to run nordvpn equivalents of tor exit nodes, then I don't see a problem.

NordVPN can't indemnify you against the cops executing a search warrant at your house, and perp walking you out in front of your neighbours because a NordVPN user used your exit node to download child abuse material.