Apparently this is the reason.
The Brooklyn Museum has become a gathering point for pro-Palestine demonstrations in which activists have claimed links between museum trustees and Israel’s military-industrial complex, claims the museum has denied. Last week, Within Our Lifetime, a pro-Palestine organisation, staged a protest at the Brooklyn Museum in which activists infilitrated the museum and several participants were arrested by police.
From https://artreview.com/homes-of-brooklyn-museum-leaders-vandalised/
If those links exist questions can be asked, but personal attacks are not done. I see no reason to disbelieve the museum, hope they catch the persons responsible for this fast.