AC Comics revived the character briefly appearing in their Femforce title as MOD. Only the M.F. Enterprises version is public domain because the copyright notice on the first issue was not in the proper location of the book which under copyright law at the time of it's publication had to be "either upon the title page or upon the first page of text of each separate number or under the title heading.According to US copyright law, all works published between 1923-1977 that did not comply with copyright law became public domain upon publication. So, because the first issue had an incorrect notice, the characters fell into the public domain. The copyright notice was not until the fifth page of the first issue.
So according to this He is, but I leave that up to the Powers That Be here to give the go ahead as I have all 6 issues.
Mr_Goldenage