Honestly, everything about MMH changes when someone new starts writing his character.
Hell, at the end of that miniseries it was decided that fire was just a psychological weakness for him (connected to the mass cremations of dead Martians - like his wife). It ended with him overcoming that weakness.
That was not followed up on at all. Then, a similar plot in JLA under Kelly was written (Fernus and the Trial by Fire), and that ended with him controlling his weakness to fire.
That immediately got ignored in all future stories.