The thing is Shock, that you must allow for the paragraph to refer to both. There is nothing wrong with attaching the antecedent where he has. But there are commentators who have noticed that the paragraph has an eerie way of reflecting the anti-messiah at the same time. anti-messiah reflecting the true one in his own devious way does make sense.
For one thing, "confirm" can also be rendered "to make harsh" which the zealots did with the old covenant.
I don't mean to remove the paragraph from the 1st century; the chart is correct about that. But you can't rule out his assumption for "he."
I don't think you know what you are talking about.
"And he shall confirm" is one word in Hebrew.
גּבר
gâbar
gaw-bar'
A primitive root; to be strong; by implication to prevail, act insolently: - exceed, confirm, be great, be mighty, prevail, put to more [strength], strengthen, be stronger, be valiant.
Meaning the subject the translators dynamically equated the pronoun to, was in fact the previous subject. The prince that shall come.
"Of the prince" "that shall come"
"nâgı̂yd nâgid" "bô'"
נגד נגיד
nâgı̂yd nâgid
naw-gheed', naw-gheed'
From H5046; a commander (as occupying the front), civil, military or religious; generally (abstract plural), honorable themes: - captain, chief, excellent thing, (chief) governor, leader, noble, prince, (chief) ruler.
בּוא
bô'
bo
A primitive root; to go or come (in a wide variety of applications): - abide, apply, attain, X be, befall, + besiege, bring (forth, in, into, to pass), call, carry, X certainly, (cause, let, thing for) to come (against, in, out, upon, to pass), depart, X doubtless again, + eat, + employ, (cause to) enter (in, into, -tering, -trance, -try), be fallen, fetch, + follow, get, give, go (down, in, to war), grant, + have, X indeed, [in-]vade, lead, lift [up], mention, pull in, put, resort, run (down), send, set, X (well) stricken [in age], X surely, take (in), way.