His first and second points about changing language and history are something both sides try to do. Trying to pin it only on the left is absurd.
His claim about shifting standards is more deceptively wrong though on several levels. In trying to define identity down to only the things he cares about he is trying to write whole groups and entire issues out of existence. In reality religions, countries and even ethnic groupings change over time also. And at the same time he is trying to say morality/ethics are constants and progressive are wrong for not having fixed standards, not accepting that they do change over time. Even religions with fixed divinely mandated laws change over time as arguments about how the laws should be implemented and enforced happen.