Answer

I don’t see why this is connected. On the contrary, from there it appears that the whole issue is only the blemish that makes it look as though the scroll is defective, but there is no fundamental problem. But there it is not dealing with a separation between the blessing and the reading as in the case at hand.
It seems to me that there is no problem with this, since the blessing is on the reading and not on the scroll, and as long as the reading is valid, we have no issue with it. I thought to bring proof for this from the reading of the Megillah. For we hold that an erased Megillah, if most of its letters remain, is valid. But as a matter of law one must read every word of the Megillah from the scroll. The question was asked: how can the reading be fulfilled with an erased Megillah? And they answered: let him read from two Megillahs, where one contains what is missing from the other.
However, see Shulchan Arukh, Orach Chayim, siman 690, paragraphs 3 and 7, and the commentaries there on paragraph 3, which answer differently.
There is also proof from the case of a Torah scroll in which a disqualifying defect is found in the middle of the reading: they switch scrolls and do not repeat the blessings.
But I did not understand why the person called up is reciting the blessing over a scroll. Let him recite his blessings, and the reader should read from the scroll in front of him. Why is another scroll needed? Is it because you were concerned about a distance of four cubits? I do not think distance is a problem, for even if there is an obligation on the person called up, he fulfills it through the reader by the rule that hearing is like responding.