Not surprising but sad.

Politicians should be excluded from what you're talking about IMO.

They're elected to serve the people and stand for our American beliefs including the freedom of speech. A political party (the DNC in this case) getting tweets removed probably isn't a 1st amendment violation. But it's really shady and anyone from government (the white house in this case) getting tweets removed is likely violating the first amendment (or coming REALLY close to it).