“Support” or any of its synonyms would be better.

“Subsist”:

1.) a) : to have existence; be b) : persist, continue

2.) To have or acquire the necessities of life (as food and clothing); especially : to nourish oneself

3 a : to hold true b : to be logically conceivable as the subject of true statements

transitive verb : to support with provisions

Also, “historians” (plural) needs “opinions” (plural)

If historians were to support their opinion the sentence would be correct in its use of ‘subjective’ rather than ‘objective’.

The sentence basically means that historians back up their personal opinions.

The sentence refers to a past event being researched, if it had indeed took place in the way commonly believed to have done so.

The structure of the supporting “argument” for, is tenuous, as it is either based on circumstantial data or data that has been interpreted in a non neutral manner.

Thus the historians purporting to adhere to this biased theory or proposition have needed to present their “facts” in a manner that sells their story.

Not lying as such but only revealing limited or particular aspects of the information available, causing it to appear to fully support their case.

As a whole, I would say that the sentence makes little sense. It is correct English, but it doesn’t really make a point… At least not a very strong one.

Also, you may want to make ‘opinion’ plural if they have different opinions.