He would have lived if, again, there hadn't been a DEM moment. Star was dead. She committed suicide. The villain got the MC to kill herself. Then he drowned her soul. The only reason she got to live was because of incomprehensible bullshit that shouldn't have worked in the slightest.
Think of it this way; Glossaryck helps Star defeat Toffee, because he's helping Star grow up. Glossaryck is also omniscient. He knows the future. So, what is he helping Star grow up to become? He's helping her develop into his future-killer. So, we know that Glossaryck is suicidal.
Why, then does he wait two entire seasons to off himself, when he could've shut down magic on his own and terminated his existence? Or, if that's too far-reaching, why did he keep himself alive in a purgatorial pocket-dimension when Toffee burned the Spellbook, if he wanted to die in the first place? If he kept himself alive because he didn't want to die, why did he save Star and give her the last bit of magic she needed to self-ressurect if he knew she would eventually kill him?
Toffee is, quite literally, the only consistent character in the entire show, and it's maddening to me that he gets reduced to meme-status. The only way Toffee could lose was by "people" behaving absolutely contradictory to who they are for literally no reason, other than because the writers created a villain so exceptional and wrote themselves into a corner so tight that even after writing him out of the show, they still have to acknowledge he was 100% right.