Posting observations by others is not recommended on iNat, but a couple individual observations will be tolerated. I agree that it is best to encourage others to make their own iNat accounts and post from there. @thomaseverest’s explanation is a good one.
I would also note that, while organizational accounts are allowed, they are not intended to be primarily for posting observations but managing things on iNat. So staff have noted that
shouldn’t really be on iNat. iNat isn’t intended to be used for institutional collections, but for observers’ own personal experiences of nature. A staff response on a similar thread (you can can many with similar questions on the forum):