None of the hammer or hammerless models were bottom eject afaik.
Last of the orig hammerless (m63) was still side eject.
The 120 was as well in the 70's.
The Marlin/ LaSalle(?) imports were standard configuration.

Might be something from their R&D shop that they thought about making.
Maybe one of the imports not unlike the Chinese M37 that Marlin toyed with importing with their name on it.
They get a few made up for show and tell, then the bosses look them over,,grumble and walk away. End of idea.