My question is this.....is this diet safe for osteoporosis prevention?

You need to make sure you are getting enough calcium--that's for sure.
Paleolithic people got calcium from the vegetables they ate, but modern
vegetables are much lower in calcium. As they were bred for taste, some
crucial nutrients were bred out of them.

My main source of calcium is bone broth, which I made regularly and use as a
seasoning when cooking as well as to make soups.  To make bone broth, you
have to boil the bones with a little bit of acid, and boil for a long time
(8-24 hours).  I usually add vinegar for the acid, but you can add citrus
juice instead.  I usually boil for 24 hours (overnight).  We make it in huge
batches and freeze it.  Add onions, carrots, parsley, and garlic for flavor.

I also take calcium supplements (when I remember), and do resistance exercise
regularly.  Resistance exercise is anything weight bearing, and is very
important for bone density.