If the person got a travel document in spite of not meeting the residency requirements, one would assume that they had an acceptable reason for why they couldn't meet them and that they could apply for a new PR card right away on the same grounds.
A PR card application takes 154 days right now, see
http://www.cic.gc.ca/english/information/times/perm-card.asp for updated info so that is about 5 months.
It is possible to apply for expedited processing of the PR card, see the link above, but if somebody doesn't meet the residency requirements and they get a PR travel document stating they are now ready to settle in Canada and the next thing they do is show up in Canada and ask for expedited processing because they need to leave, that may not look too good for them.
I do not think that the passport needs to be renewed before applying for the PR card necessarily and it is ok to enter Canada with a passport validity less than 6 months if you are a PR but keep in mind that immigration may want to see the old passport so if you think that your embassy will keep it when they give you a new one, make sure you copy all the pages from it first.