Why would that be ironic ? It's ensuring others receive the same freedom for the copy you make of the page, which is also the essence of the GPL license, and the whole philosophy of the FSF.
My issue is with the no-modification part. This is the exact argument he gives for not using some software - that users are not free to modify the software and hence it is malicious.
Have you heard of the FSF? It's not called the free everything foundation for a reason. There's no irony or contradiction here.