If we're gonna discuss Jude, for the sake of simplicity, call me Tim.
Anyway, you restated my exact point. Just because Jude quotes 1 Enoch, which was undoubtedly well-known to his audience, does not indicate he agreed with the whole thing.
When I speak at chruch or crusade, sometimes I'll use a movie quote or something that comes to mind. If I quote CS Lewis, does that mean I agree with every word he taught? (No, I'm a Calvinist, he a universalist). What if I quote Ayn Rand? No, I'm not an objectivist. How 'bout when I use Greek mythology for a word picture? (e.g. the sword of Damocles.) Or Shakespeare?
You see my point?
Actually, I exactly agree with you. Just because a portion is cited doesn't mean one should go beyond that portion. BUT ONE CAN go INTO the portion cited.
However, Jude did cite 1Enoch. It's so clear it screams at you. That's why the scholars ALL go with it. It's too obvious.
Jude 1:14 quotes the book of 1 Enoch...a DIRECT QUOTATION.
1 Enoch 2:1 Behold, he comes with ten thousands of his saints, to execute judgment upon them, and destroy the wicked, and reprove all the carnal for everything which the sinful and ungodly have done, and committed against him. (2) (2) Quoted by Jude, vss. 14, 15.