Not supported by the evidence though. The previous post by this author had a link that was struck through, as I alluded to, but the link there does work. While I can’t swear that it did work, I’m sticking with: markup fail.
As fun as puri.sm is, if you were a US-headquartered company called Purism, wouldn’t you register purism.com? (and it does appear to be registered) That means that the link might be correct and the DNS and HTTP config is wrong. Needs more investigation, which I will leave to Purism. Of course you are correct that the sensible thing is just to use a domain in the link that actually works. 
Speaking as one who operates a bunch of domains / web sites, I would just redirect purism.com to puri.sm if the latter is the branding that they want, or treat the domains as alternatives (reflecting identical content) if they don’t care so much about the branding and just want URLs to work.