You're right that Doom was originally released under the Doom Source License, which had a non-commercial-use clause, but it's since been re-released under the G

You're right that Doom was originally released under the Doom Source License, which had a non-commercial-use clause, but it's since been re-released under the GPLv2. But even so, it's irrelevant because all Romero is distributing here is a WAD file, not a modification of Doom itself.