At San Thomas the sand is very soft and fine so I would find it very hard to walk on with a stick if at all but you do have a paved pavement running along the back of the beach and wheelchair access could be OK using the wooded slatted paths that go right down onto the sand so making it a very short step/lift onto the beach.
Bare in mind I’m talking from a 12 year old memory of a non disabled person I was then but with Google Street and Earth view you can get an idea of the conditions there today.