Does anyone know why this game was unlicensed? I tried googling it and found nothing. Can you give me a link if you find or know of something? Thank you.

um nintendocaprisun did a lp about it i think he did

Who told you it's unlicensed? Nintendo themselves published it.

If you're the same guy asking about Nintendo's N64 official lists a few days ago... it's unlisted because Nintendo screwed up their official lists. F-Zero X is also missing from that list (and about 18 other licensed games) (only listed as a Virtual Console game, though the original F-Zero does properly have separate entries as a SNES game and a Wii VC game)
Oddly enough, an older PDF version of Nintendo's list (from the GC-era Nintendo website) listed Conker's Bad Fur Day and StarFox 64 twice each. That one was only missing 6 games.
The current online version added 4 of those missing games (leaving only International Superstar Soccer 2000 and Razor Freestyle Scooter still unlisted), but is missing 18 more games (296 games - 277 entries - 1 because Chef's Luv Shack is listed twice).

(yes, I realize I might have told you that it was because it was unlicensed. Turns out the NES and SNES lists were a little better made than the N64.)

It is licensed

Actually, Rare published it themselfs and THQ published it in EU.

What? Rare never published games, they only developed them. I don't know why it says "PUBLISHED BY RAREWARE" on the box. Because it has Nintendo's contact address on the box, would really suggest it is a Nintendo published game.
(also that additional "NOT APPROPRIATE FOR MINORS" warning, along with the ESRB rating really smells of over-protective Nintendo.
Then again, I guess half the game description on the back of the box is also an extreme-content warning.)

I am pretty sure Rare has published Jet Force Gemini themselves........