Not really, CSS and HTML are still working when you turn off JS. I am totally fine with people not being able to participate actively in the forum but they should at least be able to read existing conversations in an acceptable formatting.
I think it is important for a forum software to allow as many people as possible to participate regardless of their browser setting decisions or limitations. Building an inclusive community is not possible if you exclude people for no reason. What I really love about discourse is the goal of bringing the two worlds of mailinglist and forum together. So I was very confused about the fact that you did not think much about inlcuding the people browsing with JS disabled by default. I am not one of them but I do not see how this fits into the philosophy.
What is the point in having a completely unstyled
<noscript> container instead of just hiding JS functionality when JS is disabled?