Sorry, but you seem to be confusing “allowed” with “suggested” i.e.
There are two important considerations when using /robots.txt:
robots can ignore your /robots.txt. Especially malware robots that scan the web for security vulnerabilities, and email address harvesters used by spammers will pay no attention.
the /robots.txt file is a publicly available file. Anyone can see what sections of your server you don't want robots to use.
So don’t try to use /robots.txt to hide information.
So though Google may not ignore the suggestion, other bots will, and robots.txt alone will not be enough to deter Profile SPAMners as indeed it hasn’t yet.