I just realized this couldn’t have been the sefer you were quoting, since you wrote that you are sure that your al hamichya did not exempt the rice since you had in mind that you didn’t want it to, and this Sefer’s safek is based on the fact that the al hamichya may have exempted the rice anyhow.
So it sounds like your sefer had a different reason for צ”ע. What was his reasoning? And what was the reasoning of your LORs who said that you needed a new bracha?