It should be noted that toolforge tools are run by volunteers, and are subject to a different privacy policy than the main wikimedia sites (that said, they are not allowed to do shady things).
You should only need an account on wikipedia not toolforge. Blame all the people who keep uploading pirated movies.
"Vetted" is a bit of an exageration (its pretty easy to get an account. Sure technically there is a process, but its an easy one).
Basically you can't openly be evil, and if someone discovers that somebody is being evil they get kicked out. Also i think there is a proxy so you can't easily collect ip addresses.
So its a step above some random website, but ultimately its closer to a third party site then it is to being real wikipedia.
Given you are all on hackernews which is basically a link aggregator for random websites, there is really no reason for this to give anyone pause.
There is also no validation whatsoever on Wikipedia accounts, email verification etc is not required.
If you're worried about trusting toolforge.org, it's run by Wikimedia, the organization behind Wikipedia.