It's almost certainly correct. I don't know Heiser from Heineken, but I do know...
Every Middle Eastern city had a patron deity. Every king over a city had a regnal name commemorating them in relation to that deity. The kings of Babylon were Nabo-nidus, and Nebu-chadnezzar and Nabo-polassar, because Nebo was the patron god of Babylon during their dynasty.
That a dynastic successor of Melchizedek has a Tsedeq/Zedek/Zadok in their name is evidence enough to conclude the matter.
Now, remind me, who was High Priest under David? And whose priestly lineage was the most important among the Levites from that time down?
Hmmm, so you suppose that the line of Zadok refers back originally to the local god of the Canaanites just because the same basic root word with the same meaning is used in both ancient languages? There are those who claim to be righteous and just but are not or were not, (Canaanites), and then there are those who truly are or were, (Tzaddokim). However, I believe "Yithro", ("His Excellency"), Raguel was the dynastic successor to Melki-Tzedek, then Moshe married into that line by way of one of seven little birdies, (Tzipporah, the daughter of "His Excellency" Raguel), then of course Yhoshua ben Nun received the charge from the Father by way of the hands of Moshe and was placed before Eleazar and the congregation, and so on from there, (for the Melki-Tzedek Elohim Priesthood is above that of Ahron and the Leviim).