That is then further confirmation that Rav Kanievsky does not maintain that the position of Copernicus is heresy. This is good news all around.
On the other hand, it is somewhat unfortunate that, according to this position, it is not resolvable bizman hazeh whether the sun revolves around the earth of vice versa. It is similarly the case that is is unknowable whether the earth is round or flat, and it is only for Moshiach to clarify this for us?! Obviously not.
I would guess that this is not a reactionary position, such that because the kofrim maintain otherwise we must maintain the possibility of the Rambam being correct. More likely, it is a matter of lack of knowledge of secular science. Dovid, the questioner and subsequent commenter, merely pointed out that one need not resort to epicycles. But he did not point out that rather compelling evidence that day and night is a result of the earth's rotation, about the Coriolis effect, about the motion of a pendulum, about stellar parallax. Likely this would require quite an involved and lengthy conversation.
Back to the first hand, who really cares? Does correct knowledge of astronomy really make one a better yerei shamayim? Does it really impact, practically, any halacha. It does not really matter. And so long as one is willing to accept the possibility of the other, and in this way not end up falsely labeling others kofrim, there seems to be little problem with all this.
Back to the second hand, here is why we should care.
There are indeed Jews who study science, and are taught this science in elementary school or high school. And so they know that the earth goes around the sun, and some of the proofs. When they encounter gemaras, or Rambams, other rabbinic sources which indicate otherwise, they are troubled. And so for these Jews, there is something they must grapple with, theologically. And then, some may arise -- such are Rabbi Slifkin, but Rabbi Slifkin was not the one with the big chiddush, but was saying things well known beforehand -- and defend our tradition by offering explanations, and how one can still respect Chazal and the integrity of Jewish tradition despite this divergence. To Jews who know science, this is great kiruv. To Jews who were ignorant of the science, this was never a problem, and so the very legitimization of the question is an attack on tradition. (And if either the heliocentric model or the geocentric model may be right, other people will assume the attitude of: how dare one assume that this illustrates Chazal were wrong on science?) And such books, even if not-kefirah, don't belong in a Jewish home.
Can one turn to the chareidi gedolim in Eretz Yisrael in such a situation to resolve such questions? Of course not! Not if they don't know enough science in the first place to legitimize the problem. They can fall back on the idea that we simply don't know.
As a separate issue, while this particular case does not appear to affect pesak, it might reveal a general lack of scientific knowledge, in cases where scientific knowledge could and should impact halacha. And knowledge of the metzius is a critical component in pesak.
So in sum, this is both encouraging and discouraging. At the least, it was not as discouraging as first appeared.