I've seen a lot of copyrighted media shared by people on Twitter who are not the owners, and this is the first time I've seen the copyright notice as shown on the president's tweet. I've seen tweets taken down at the request of their authors (or retweets from their original authors), but not in this form - that's what makes it seem (to me) more suspect. If this were happening regularly with the millions of other daily instances (from celebrities to countless other regular users), it would be a little more defensible. The objection here isn't to DMCA takedown requests; it's the blatant (and politically-motivated) inconsistency in the application of their rules.