FAKE NEWS.
How to spot fake news:
1. The source cited is not a legitimate news organization (CNN, NYT, WAPO, AP, REUTERS, FOXNEWS, ABC, NBC, CBS, BBC, etc.).
2. A Google search reveals that the story is not reported by any legitimate news organization.
For THIS story, a Google search revealed a Politico article stating this alt-right story making the rounds, and that it is false. It's a KNOWN FAKE NEWS.
Fake news stories are predominantly on the right. They were generated a lot during the campaign (Breitbart, DailyCaller, other far right websites, the Trump-son-in-law-owned website that pretends to be "news").
I'm sure some fake news must have been generated on the left, but I haven't seen any.
Fake news stories are also spotted because they don't make sense, or they go against the norm for a person's behavior. It is not the norm that Dems in Congress are disrespectful by not standing to honor a veteran, fallen soldier, the POTUS, etc. Dems are fairly with-it, when it comes to decorum.
Compare with the right: Yelling "YOU LIE!" to the President during his State of the Union address, refusing to shake hands with a liberal-leaning Supreme Court Justice (McConnell refused to shake Brenner's hand before a State of the Union address).