So who made you moral arbiter then? Who are you to decide where the 'line' is?
And, perhaps, people are being deliberately disrespectful because Thatcher actually deserves it. You can see plenty of intellingent, rational, reasonable, compassionate people letting their hatred for Thatcher out, and rightly so. It doesn't reflect negatively on those people in any way. This was always going to happen and it's been a long time coming.
The emotion will die down in a day or two but her destructive legacy will linger long. There absolutely needs to be a counter-balance to the anticipated eulogising and whitewashing of yet another sociopathic UK leader. The woman was heinous.
This is not some ned in a tracksuit, throwing an empty beer bottle at a serial-killer's police van type moment. There is a power, a necessity, and a certain beauty to most of the reaction to her death. Some people are judging the overall reaction by the actions of a very few who don't represent the majority, and shouldn't be seen to be detracting from what is, in my view, valid venting of emotion.