I don't disagree the crowd size issue is pretty silly.

That said, if some gov't agency started Tweeting negative things about the Obama administration after his inauguration, would any talk about a "chilling effect" if he told them to stop? I'm not his biggest fan, but I wouldn't fault him for that.

The job of the National Parks service is pretty clear. Tweeting their political opinions using their employer's account are not one of them.