Yes, for conventional strikes. But if the ALBMs are intended to have a nuclear role, a situation may arise in which there isn't time to launch a massive aerial campaign to destroy air defenses in Japan. Stealth would help the bomber get through in that situation.
Eastern Russia isn't empty, and the bulk of the VKS' fighter strength is strung along the border with China. It would be great if Russia would allow overflights, but it isn't a good idea to depend on that, especially with a nuclear strike system.
You do it together. Stealth doesn't work
that well in fighter-augmented IADS without support anyway. I.e. for just that mission, low altitude + support is quite desirable.
Also, number of fighter rgts in eastern Russia is minimal (single digit of them; I don't think Russian forces in Eastern MD can even take on Japan w/o significant reinforcements from the west), and unless Russia will go full blue 8-nations alliance style, stripping western frontier, i don't think it will change. China is guarding Russia's rear as much as Russia is guarding China's now. It's a very clear mutual benefit.
With advancements in ballistic missile accuracy, this seems questionable. Have there been any actual indications the H-20 might be intended to operate *in* North American airspace? In this day and age, what advantage would there be to dropping bombs from directly over targets, as opposed to hitting them with ballistic or cruise missiles?
Gravity bomb(even with kit/wings) is basically all warhead. Everything is effective weight, i.e. transport advantage is significant.
As soon as you start adding "true" rocket engine, you add relatively high tech parasite weight, that isn't that warhead.
For example, one JL-1 ALBM may equal couple dozen B-61s, while delivering just one.
If stealth bomber is more survivable than single ALBM(which isn't exactly a big if, esp. since USA has continental mid-course ABM) - it makes sense to carry more.
Second advantage is sensors - manned aircraft within LOS is by default a strike/reconnaissance system, that can observe space around it, make targeting decisions(even against moving targets), choose suitable weapons(no need to evaporate everything, when just SDB/a2a can produce desired effect) and evaluate results - everything immediately.
Stand off carriers are effectively delivery platforms only - they're blind, their targeting decisions aren't even theirs. At best they're as fresh as your weapons' ToT/last OtA(space) update.
But since we're talking nuclear war, and space(or even command facilities) can be gone completely - this delay starts growing, at worst becoming map targeting outright. Which is obviously not ideal and completely lacks feedback (like, how you even know w/o recon feed, where you weapons worked, where they didn't.)
Furthermore, there's a weapon choice.
I'd suggest JL-1 is the best choice for H-6N, all things considered. Why？
It isn't an intercontinental bomber by default, and its bomb bay is small(or even filled with additional fuel). External weapons are a careful consideration of drag coefficient v pen chance, which is a very tough equation for a small heavy bomber.
If not because of H-6 platform, i personally think China would've went for very long range LO cruise missiles, like Russia. They just make it further using much less volume and weight. For example, on a same mission H-6N will prosecute with 1 JL-1, Tu-95 (through sheer range advantage) will launch 4 or maybe even 8 weapons, and Tu-160(where everything is internal) - 12. Yes, with individually worse chances of getting to the targets. But it's 12.
And with mix of tactical missiles and gravity bombs, CW bombers could rival boomers in their destructive might. Severa, dozens of warheads per bomber are totally doable.
