His estate decided to modify the property they own to exclude words they found offensive. Do the owners of a book with the rights to its publication not have the right to publish whatever they like?
The only thing I don't like about this is copyright keeps his books from being republished by anyone but his estate. Copyright lasts far too long.
They had legal rights, sure. But moral rights? No. Any author would turn in their grave at the mere thought of a publishing house bowdlerizing their work after they're no longer around to defend it.