Doing a little reading... obviously I'm no expert on this. But for what it's worth...
The NOC for diplomat is 4168, under the heading 'Program officers unique to government'. This is a class A job, which would typically qualify and I can see nothing in the legal notes for CEC that would exclude you (from a quick looking over).
I think you'll be fine, assuming you pass the rest of the eligibility and get enough points for an ITA. Hopefully someone can else confirm...
HRSDC link to NOC 4168 (for diplomat, look under the full list of job titles):
http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/ProfileDescription.aspx?val=4&val1=4168&val27=diplomat&val28=0&val29=0&val30=2&val31=2&val32=2&val33=2&val34=2&val35=2&val36=2&val37=2&val38=1&val39=0&val40=Section
CIC link to verify job skill level:
http://www.cic.gc.ca/english/immigrate/skilled/noc.asp
CIC link about not requiring a work permit as a diplomat:
http://www.cic.gc.ca/english/resources/tools/temp/work/permit/representatives.asp
CEC eligibility:
http://laws-lois.justice.gc.ca/eng/regulations/SOR-2002-227/page-41.html