First off, I didn’t say I think it was necessary to begin the siyum with singing Hatikvah. I wouldn’t have a problem with it, but I don’t think it would be necessary, especially in Chu’l.
Health, I am not a Novi, but here are some sources for my assertion. I don’t say you must follow them, but these seem sufficient for my assertion (H/T Rav Dov Lipman)
Rabbi Akiva Eiger taught that if we succeed in growing fruit in Israel then the final geulah is imminent (as related by his student, Rav Zvi Hirsch Kalischer, Shivat Zion, volume 2, pp. 51-52).
Meseches Megilla (17b) … the final geulah begins with the in gathering of the exiles, followed by t e flourishing of the fruits of Israel, and concludes with the arrival of the Moshiach and the rebuilding of the Beis Hamikdosh.
Beyond this, I follow the teaching of my Rosh Yeshiva, of my Father a’h and my grandfather a’h also pointing in the same direction.