Whales have been beaching themselves all over the world forever before people. We just happen to be around to witness it. Entirely possible our recent civilization has contributed to an uptick of beaching, but we didn't start it. It's incredibly sad when it happens.
Since it's natural event, I'd spread them out as well as tow some back in the water to feed the rest of the wildlife. Mother Nature has always taken care of her corpses.
Like the climate. It's always been there and cycles. But our society is definitely messing big time with those cycles.