Should DFAIT institute it's own Diplomatic Protection Service? Absolutely not. Even the American's can't pull this off with all of their resources hence their reliance on Blackwater and others and I'm talking world wide, not just Iraq and Afghanistan. DFAIT also had their own Security Guard program in the not so distant past which was replaced by MSGU and there is a reason the transition to MSGU happened...
If done right, the program would be so small and specialized that it would soon become a revolving door as people were trained, deployed, made contacts and left for PMCs to make the big bucks. The military/public service will never be in a position to compete with private companies in the realm of salaries for those who are truely good at this. The end result would be any DFAIT specific program would end up having too many guys who couldn't make the grade to get to the big leagues, which is not what you want, although I'm sure some decent guys would remain out of a sense of duty and loyalty perhaps.
The MOU in place between DND and DFAIT for the current MSGU setup specifically forbids MSGU to provide CPP. They can provide "Escort" to various degrees and are doing so and have done so in the past, but full blown CPP is not allowed. As I've said in another thread, sometimes the line is very blurred as to what is being conducted but at the end of the day, DFAIT cannot currently ask for CPP from DND assets without going to another MOU.
I have had a discussion with someone in the know a few years ago when the Branch was getting back into the CPP business that DFAIT was discussing getting CPP into Kabul, but it would have been under a seperate mandate from MSGU and would have been specific to Kabul. For whatever reason it never came off but it certainly would have made for an interesting situation.