The mismatch between the job as actually performed and the listed profession's duties, followed closely by holding a credential that is not the one the Appendix 2 entry names. Citizenship is rarely the problem for Canadians; fit is.
Test fit on duties and on the named credential, separately
Start with the duties. Write out what the person will do in a typical month in the United States and ask whether a reader would recognize those tasks as the listed profession's work. A forester who spends most of the week operating a harvester is doing a trade, whatever the title says.
Then test the credential. Appendix 2 names the acceptable qualification for each occupation, and some entries accept a licence, some a degree, some a diploma plus experience. Holding a related qualification is not holding the named one.
If either test fails, the honest response is to ask the employer whether the role can be defined truthfully in a way that fits, or whether another category should be examined. Do not rewrite the duties to match; the officer will ask about the real work, and the applicant will have to describe it.