Yep you're right, the PDF definitely states that. Thanks for the link.
My understanding about that though is that it is basically a recommendation/suggestion, it doesn't necessarily mean one must be in the US for no less than 60 days before intending to travel like the OP's post comes across (that's the way it comes cross to me anyway). When filing for a re-entry permit, one needs to allow enough time for USCIS to receive and formally accept the application - acceptance is evidenced by the issuance of a NOA receipt, and to complete the biometrics at least before departing from the US. It's intended to let people like the OP know they need more than 2 weeks to complete the initial process, not necessarily that they must be in the US for no less than 60 days.