I looked into this question a bit and discovered that the Freeman family did own several large farms in the vicinity of Lot 60 in Amherst. The patriarch of the family, William Freeman (1741-1801) had died and left several properties to his children. His wife Jerusha Youmans (1748-1812) had died in 1812, the same year DesBarres arrived. Philip Freeman (1783-1837) and his brother Joshua Freeman (1774-1863) eventually moved to Halton, Ontario so it does seem plausible that they might want to rent their properties during a transitional time. If anyone from the Ontario branch of the Freeman family would like to collaborate on this question, please comment below! I would be particularly interested to know when the Freeman brothers departed for Ontario.
The Morse testimony and expense accounts can be read here:
DesBarres Papers, Series 5 (M.G. 23, F1-5, Vol. 25) Estate papers and suits, 1824-1857. DesBarres Fonds, Reel C-1461, document #6605, image 426. One of the expense account lines mentioning Freeman is on image 375 in the same film. Use the arrow keys to navigate within the file.
William Freeman's probate papers are here, and Jerusha's are here.