The ****? This is a High-End. Literally, anyone who's in the Top 5 in Japan's hero rank would scale to it. Unless you somehow have evidence suggesting it's not a high-end, this is just another reach.
The Nomu arguably survived only because it can regenerate from such damage (Hood survived ripping off his own head, so in theory even if his body was hit by a much stronger attack he would regenerate so long as his head remained intract).
But the thing is that Hood is likely the only one with notable regeneration. Hell, we don't even know if all of the high-end Nomu have regeneration, to begin with. It's not really shown or indicated outside of Hood.
But fine, let's bite the bullet here. Even if we assume the high-end Nomu only survived because of generation,
it wasn't instantly killed. Meaning, that it's not like it's 100x weaker than the nuke itself. At best, you can say it heavily downscales to the point of being one-shotted, but even that would still place it within
High 7-A.