DY, they aren’t getting upset they are getting riled up. The first is what someone else does to you, the latter is what you do yourself. They never cared all that much about Har Habayis. When Jews started coming they turned it into their third holiest site. Now they can enjoy playing basketball on their “third holiest site.”
The only mistake with regard to the Har Habayis was to hand it to them after the six day war. Like the Medrash says, whoever tried making peace with them landed up with embarrassment. This has been proven over and over. We are forced to pretend we have hope for peace as long as the Western world thinks there is hope. We might have to go along with the proposals but we already know the outcome.