Well, some Democratic Party politicians attended, but optically, they probably should have skipped. They sat there, and sulked. They just looked like the anti-American losers that they are. They're now trying to play off not standing to affirm that they think they should serve Americans first as "Well, that type of thing happens at every SOTU speech".
Really. What did they stand to lose by standing at that moment? They'd have lost the lunatic fringe of their voters, but those voters aren't the majority, and they're never going to be placated anyway. They're scum. They make everything they touch dirty.