Child in Isaiah 7:16

Isa 7:16 KJV
For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings.


Who is the child here? Is this Immanuel on Isa 7:14 or Shearjashub, Isaiah's son on Isa 7:3?
I would rather agree with Matthew Henry's interpretation that it is Shearjashub.

Here is another sign in particular of the speedy destruction of these potent princes that were now a terror to Judah, v. 16. "Before this child (so it should be read), this child which I have now in my arms’’ (he means not Immanuel, but Shear-jashub his own son, whom he was ordered to take with him for a sign, v. 3), "before this child shall know how to refuse the evil and choose the good’’ (and those who saw what his present stature and forwardness were would easily conjecture how long that would be), "before this child be three or four years older, the land that thou abhorrest, these confederate forces of Israelites and Syrians, which thou hast such an enmity to and standest in such dread of, shall be forsaken of both their kings, both Pekah and Rezin,’’ who were in so close an alliance that they seemed as if they were the kings of but one kingdom. This was fully accomplished; for within two or three years after this, Hoshea conspired against Pekah, and slew him (2 Ki. 15:30), and, before that, the king of Assyria took Damascus, and slew Rezin, 2 Ki. 16:9. Nay, there was a present event, which happened immediately, and when this child carried the prediction of in his name, which was a pledge and earnest of this future event. Shear-jashub signifies The remnant shall return, which doubtless points at the wonderful return of those 200,000 captives whom Pekah and Rezin had carried away, who were brought back, not by might or power, but by the Spirit of the Lord of hosts. Read the story,2 Chr. 28:8–15. The prophetical naming of this child having thus had its accomplishment, no doubt this, which was further added concerning him, should have its accomplishment likewise, that Syria and Israel should be deprived of both their kings. One mercy from God encourages us to hope for another, if it engages us to prepare for another.