I wouldn't say that. Rune Thor is more powerful than Odin was. Plus, the idea that the Sentry is at Galactus' level is unproven and totally without context, taken solely from an offhand comment from another character. For all we know, it could refer to the Sentry fending off a nearly starved Galactus, which regular ol' Thor has done himself. So far, the most impressive feats I've seen from the Sentry or the Void (whose power is implicitly equal to the Sentry's) are practically killing Terrax with one hit and shattering all of the Hulk's bones, both of which are well within Rune Thor's power given the way he handled Mangog.
Agreed. We DO know there was a confrontation, and I did make the mention that Sentry might be basically surviving Galactus, rather than flat out punching out Galactus prior. Given the entire context of that mini though, it would be slightly contrived and grasping at the idea of it altogether, rather than thinking his power levels operated in the extreme measure.
However, we've never seen Sentry or the Void exert themselves ever, much like Rune Thor. We know Sentry's never even come close to tapping his power potential, and we know the Void is characteristically weaker than the Sentry. All we know is that even at those levels, he was capable of standing solo against Galactus. And if those were to be taken in case (with his powers being held at lower reserves) it stands to reason he did more than just hold off Galactus or survive Galactus. At that point, Galactus was being written as the guy who would launch extremely massive attacks at his opponents, rather than his first appearances, where he'd barely decimate buildings. And in all truth, Spidey probably would've said something like, "led the fight against Galactus" if Galactus were weakened, giving the idea of "Fought Galactus to a standstill" that nobody else was capable of the task itself. Much like Thor or Rune Thor would be regarded as, as both would have taken on Galactus' brunt solo, rather than in any form of team due to his power and durability.
What we also know is that the Sentry's powers are not merely physically based, and has shown powers that go above and beyond his own "punch and kill" abilities we most often attribute to him. Given that his powers are chronological, and can even rearrange matter quite easily without any form of direct contact (to the point he doesn't actually have to be there), his vast variety of powers, and upper levels are probably far far far FAR above anything we've seen him do.
What we DO know of the Sentry, is that the Marvels seem to regard him as some sort of ungodly huge powerhouse that people normally don't go around messing with unless they probably wish to die. (And though it was just a cheap cop out to explain why there's no Sentry villans) the ONLY Sentry villan to even still be around is the Void, out of the few dozen villans he most likely had. Most regard him as their ace, and definitely most who DO remember him, walk around him with eggshells due to his power levels. It's probably why his power is alluded to a million exploding suns. We don't see him hurt, ever. Not even in his minis, do we see him hurt at all. Even when he was in the middle of those nuclear explosions and the station explosion, the worst is his cape is in tatters. We even know the Sentry can even fend off the power of a cosmic cube without any injury.
So, all we POSITIVELY know is that currently, the Sentry has only had to deal with Earthly problems at the moment (most of which provided by Bendis basically, and nothing much in his minis except for how easy it is for him to take care of enemies entire teams have problems with) which wouldn't even begin to test his upper eschelons of power (or even his mid ones) much like how we're stuck with Rune Thor's power levels of unknowing.
I would not completely discount Rune Thor against Galactus. He did everything with great ease.
Galactus doesn't usually put much effort into anything himself.
One thing to remember about Terrax, his powers are not at the levels they were when he was a herald. Galactus took those powers away. Doom gave him a weaker version of his former powers. Thor even at his normal power level defeated Galactus.
Actually, Terrax is still a power cosmic powerhouse easily capable of planetary destruction and such.
And as for defeating Galactus? Umm... When?