Jetman Epilogue's Canonicity

The Jetman Manga Epilogue is kind of a tribute to Gatchaman in some way like the Jetmen using open helmets similar to that of Gatchaman and that Radiguet somewhat resembles Egobossler (but with the absence of a Sosai X equivalent) as well as Ruma being force-grown is similar to that of Gel Sadra in Gatchaman as well.

Also there was the unused concept of the replacement for Joe Asakura. In Gatchaman, Joe Asakura was supposed to be replaced by a new member but he was instead, restored as a cyborg. In here Gai Yuuki is pronounced dead (but what happened to him is unknown in the super sentai universe) and he gets replaced.

The manga also had other inconsistencies like the return of the Neo-Jetmen (which they gave their energies to the Jetmen for them to fight Vyram back) as well as the return of the Jetmen's mecha (they were badly damaged but then they could have been repaired but then in sentai, some mecha do get destroyed like those in Carranger a series that came after Ohranger).

Since it was never shown in TV (well by that time, both actors Kotaro Tanaka and Rika Kishida finally got married and were on their honeymoon) so I can consider it non-canon just like the Kakuranger vs. Ohranger movie.