I disagree. Having spent 10 years in the beltway, I can tell you that these restrictions will greatly annoy virtually every member of Congress and more importantly their staff who all travel frequently. Some go home every week, and IAD has always been one of the worst TSA checkpoints, and clearly not going to get any better. The ban on bottled water is particularly absurd and one I think that is unlikely to last for long. The ban on most toiletries is almost as ridiculous and basically forces everyone to check at least one item - so I predict that will be modified as well.
I don't disagree that Congress won't eventually get pissed off. My point is the timing -- summer recess, numerous appropriations and authorization bills due, and a mid-term election coming up.