How do syntax errors dissuade you from the proposal? Is not design separate from implementation? Is it not true that a well-designed specification, proposal, etc. can be poorly implemented?
If you got a job offer that was riddled with spelling mistakes and had the wrong name, would that inspire confidence in your future place of work? It's not a huge stretch of the imagination that small, obvious issues could mean larger, more complex issues lurking.
I'd say "riddled with spelling mistakes" is a bit strong in our example (I realise you weren't claiming that about the site).
I got it out early to get some feedback. The 404 spec link is a bad one (since fixed) but the typo in the DNS record is forgivable I think – very impressed anyone spotted that.