Unfortunately it's been shown time and time through the posts on this forum again that immigration officers don't always have the right answers for more complicated questions (if I had a quarter for every wrong answer I heard about here...). This would be one example where bad information is being provided. IECs unfortunately cannot be extended and there is no implied status. We've now seen at least two people on this forum who have run into problems with their applications because they thought they had implied status but have now been told by CIC that they were working illegally. You can read about one of those stories here:
http://www.canadavisa.com/canada-immigration-discussion-board/apply-inland-after-iec-expire-keep-working-and-now-aip-refuse-t163087.0.html
I will try to find the second thread. In that example, the person already had their PR visa but was refused landing due to the illegal work (again, they thought that implied status applied to IECs and were told it definitely does not because IEC are not extendable).
We now also have TV proof (if that counts for anything). A recent episode of the reality show that follows CBSA agents around once again proves that implied status does not apply to IECs by showing a situation where someone runs into immigration problems based on this false assumption. Obviously you're free to do as you wish. But there is a chance this could end poorly if you continue working.
