I didn't mean to imply that you share your sources; I was simply sharing the NARA source for Texans serving under Forrest in 1861-62. My offer to help with Texas service records and save you a trip to DC still stands.
If any of Forrest's biographers have mentioned anything along those lines, I have overlooked it. However, it would be fair to assume that Forrest was obliged to obey the law, under which only slave owners or state governments had the right to grant freedom to any slave.