This is an invalid argument. There is no such thing as “tense” in biblical Hebrew. (Modern Hebrew, on the other hand, does have tenses.) Biblical Hebrew is not a “tense” language. Modern grammarians recognize that it is an “aspectual” language. This means that the same form of a verb can be translated as either past, present, or future depending on the context and various grammatical cues. The most well known grammatical cue is the “vav-consecutive” that makes an imperfective verb to refer to the past.
Therefore it is wrong to say that Isaiah 53 or other prophecies are in the “past tense.” Biblical Hebrew has no tenses. There are many examples of what is wrongly called the “past tense” form (properly called “the perfective” or “perfect”) being used for future time.
This fact was recognized by the medieval commentators as well as by modern grammarians, as shown by the following citations.
Medieval Jewish grammarian and commentator David Kimchi on the prophets’ use of the perfect for future events:
“The matter is as clear as though it had already passed.”
David Kimchi, Sefer Mikhlol. Cited in Waltke, Bruce K. and O’Connor, Michael Patrick. An Introduction to Biblical Hebrew Syntax (Winona Lake, IN: Eisenbrauns, 1990), p. 464 n. 45. They reference Leslie McCall, The Enigma of the Hebrew Verbal System: Solutions From Ewald to the Present (Sheffield: Almond, 1982), p. 8.
Rabbi Isaac ben Yedaiah (13th century)
[The rabbis] of blessed memory followed, in these words of theirs, in the paths of the prophets who speak of something which will happen in the future in the language of the past. Since they saw in prophetic vision that which was to occur in the future, they spoke about it in the past tense and testified firmly that it had happened, to teach the certainty of his [God’s] words – may he be blessed – and his positive promise that can never change and his beneficent message that will not be altered.
Saperstein, Marc. “The Works of R. Isaac b. Yedaiah.” Ph.D. dissertation, Harvard University, 1977, pp. 481–82. Cited in Daggers of Faith by Robert Chazan, Berkeley: UC Press, 1989, p. 87.
From the standard grammar of Biblical Hebrew, Gesenius’ Hebrew Grammar (section 106n, pp. 312–313):
More particularly the uses of the perfect may be distinguished as follows: – …To express facts which are undoubtedly imminent, and, therefore in the imagination of the speaker, already accomplished (perfectum confidentiae), e.g., Nu. 17:27, behold, we perish ,we are undone, we are all undone. Gn. 30:13, Is. 6:5 (I am undone), Pr. 4:2…. This use of the perfect occurs most frequently in prophetic language (perfectum propheticum). The prophet so transports himself in imagination into the future that he describes the future event as if it had been already seen or heard by him, e.g. Is. 5:13 therefore my people are gone into captivity; 9:1ff.,10:28,11:9…; 19:7, Jb. 5:20, 2 Ch. 20:37. Not infrequently the imperfect interchanges with such perfects either in the parallel member or further on in the narrative.