The dedicated page for this game doesn't tell anything about its end goals, so we can't rely on official requirements regarding game end here. Which options do we have then?
Splitting this into 2 movies doesn't make much sense, because the game has no SRAM, therefore no newgame+ kinda branch. So we either use an emulator savestate, which is
outright banned, or play the game twice. Or refuse the second quest altogether, just like with Gosts'n'Goblins.
But unlike in GnG, this game features significant gameplay difference, so beating it the second time showcases more of what it has to offer. Even if the levels are the same, main mechanic is still different. And yes, since the game explicitly recognizes your second completion by stopping itself, we can say that it's an intended stopping point for this game.
Some games allow SRAM or passwords to be used to reach the second quest easier, and maybe the original plan for this game was indeed to provide such a method, but as it is right now, there's no other way to reach the full stop. So we just have to play the game twice.
And drop the branch label.