The point was that "Leave EU" - a group dedicated to leaving the EU and removing the rights of UK people to register a .eu domain - has itself got an eu domain

The point was that "Leave EU" - a group dedicated to leaving the EU and removing the rights of UK people to register a .eu domain - has itself got an eu domain which is unaffected by the leave process because it's registered via an EU company. Perhaps "hypocritically" rather than "ironically" may have been more accurate, but certainly would have been more political. To be honest I can't think of any other .eu domains other than leave.eu.