They could be, but they have, I would suggest, different purposes. One should not presume that the people who come under the seasonal agricultural worker program want to immigrate to Canada. They have families in their home countries. The money they bring back to their host societies has been demonstrated to improve education outcomes for children, and so forth. Some percentage of them may wish to settle in Canada.
We do have to remember, though, that in some of those occupations, once they become permanent residents they will generally, like Canadians, not be ready and available to do that work. The seasonal agricultural worker program brings in people to do jobs that Canadians have chosen not to do. All the evidence would suggest that once permanent resident status is obtained, they are not likely to remain seasonal agricultural workers. They will migrate to other permanent occupations.