--- The item 6 in the first post is correct and is based on the feedback from applicants who actually got rejected !! I am sure that they were not fulfilling the CIC Clause which you pointed i.e. "apply within 6 months of the issuance of PCC".
I have taken strict stance in writing few items of the first post, after reading the consensus of the community, and to avoid rejection situations to begin with ! The point number 6 WILL NEVER FAIL you, because once you apply for the PCC after leaving the Country, your PCC is valid no matter how old it is and you will never face rejection !!
--- The clause from CIC quoted above cannot be challenged and is correct ! In the post that you have mentioned: My Advise to OP was based on a particular situation of the OP as he has to visit for a month (as far as I remember) and he was ready to apply for eAPR, so he was fulfilling the CIC clause "apply within 6 months".
You have to be careful while applying a particular on yourself which was given to someone else, as sometimes (very rarely) I am giving personal advise to the people based on their particular case and they can not be generalized !
Moreover, the list of rejection reasons of this thread must have few flaws, and is not complete! I hope I have clarified your confusion, and thank you for bringing this up, so that others can learn !