I do not live in Canada and I am not very well versed in the broadcast content laws so my opinion is solely based on personal philosophy. That said, I am not at all in favor of any legislation mandating certain content be aired period.
We have "Public Radio" stations in the US. Mostly, and I know there are plenty examples of abuse of this system, these stations are supported by the listeners. The station I am a member of, and support by my financial contributions (as meager as they are) as well as volunteering at different station events is WFUV. This is the Fordham University radio station. This station responds to the musical wants of their listeners. There are a few "underwriting" announcements (corporate sponsors) each day but two thirds of the operating budget comes from listener donations. I answer the phones during the pledge drives and I can attest to the fact that the station has a listening "community". In reality if the musical content was not in accordance with the listeners' desires the station would either fold or only air "canned program" content purchased from either NPR or other air show clearing houses whilst supported solely by the university.
There is plenty of "new", "local", as well as "not very much heard" talent aired on a continuous basis. That is why the listener support stays high enough to keep the station on the air. In this system each community, by way of their support or lack there of, can determine the content they wish to be aired. To my way of thinking a much better way of protecting liberties than mandated content.