There is a really big issue with this for me as fundamentally NK should not be banned from putting something into space, why should it be dictated to by other nations that have already done so?
because they can?
Because those nations want to maintain their security and value it above that of others?
Same reason we don't let any one own a machine gun but let the military use them.
Why should we be dictated as to what we can do on a world stage, more importantly who's going to?
Japan is also worried more than the US, and iirc has stated it may look into developing it's own military nuclear program in response so it's also an issue of trying to control proliferation (after all while every where may be stable now what about in 50 years, or a hundred years? best to try and reduce numbers while it's controllable.)
Then there's also the possibility they could trade the information like Pakistan did with nuclear tech and north Korea, NK might not use an ICBM to nuke America but whoever they trade the tech to could use a long range missile to conventionally strike someone else.
There are lots of reasons, to think it's just about direct threat of a missile to the Us is a laughable over simplification.
Oh and one last thing, if they get a working long range nuclear capability to strike the continental US, do you think the US will step in if they start shelling Seoul or try invading the south?