Seems like it's what the museum does, so it's to be expected:
"The Haus der Geschichte is a museum of contemporary history with the motto “Experience history.” It shows exhibits on German life, politics, economy, and culture from 1945 until the present day, including objects like the door of a German armed forces vehicle that was shot in Afghanistan, and pieces of debris from the Twin Towers."
The mayor doesn't fancy it just yet though:
https://news.artnet.com/art-world/berlin-mayor-debate-terror-attack-truck-museum-806030
I suppose it is an attempt to contextualise the attack within a broader historical view, which seems like a good thing to do, generally.
Still, is it time? Probably not yet. But then, would you want it to be sent to landfill? There's comfort to the bereaved that someone wants to remember. The museums that want this kind of thing probably have to get in early to avoid missing out.
Interesting though - what to remember when it comes to national/international tragedy?