The package instructions list 'playing with pets' as one of the intended
purposes of the pointer.  I've used it quite well with cats, and I'd say the
only reason not to use it with ferrets is that they don't seem to respond to
it.  At least, Hershey doesn't.
 
I've hit myself in the eye with the beam on occasion and incidental
exposures are harmless.  I wouldn't suggest aiming for a ferret's eye, but
it isn't dangerous.  The warning on the pointer is just something legally
required, much like the warning on the application for a ferret license, and
has no bearing on reality.
 
E.S., Hershey, and happy memories of Nestle'
[Posted in FML issue 1404]