Yes David, in respect of this particular museum, and perhaps other public museums in the USA, you are correct.
Here is a link to the the Met's balance sheet,. It is a very superficial balance sheet and we do not have access to how it was compiled, but even so, we can see that the bulk of funding is not coming from any government base.
http://www.guidestar.org/pqShowGsRep...e&npoId=390161
However, wherever that funding is coming from there is one thing that is still true, and that is that any museum will only function in accordance with the wishes of the community in which it exists.
In a community that funds its museums from public money, those funds are inextricably linked to public perception of political endeavour.
Perhaps the Met and other museums in the USA do not have this same political agenda with which to comply, but they must still satisfy public demands. If they do not, it is inevitable that they become irrelevant to the community and they gradually spiral down into non-existance.
Here with the Met we can see my second reason for non display and non maintenance of weaponry taking a dominant role in the decisions made by the museum's administrators:- current societal attitudes.
Those attitudes dictate the way in which any organisation will function, be it an organisation formed to collect garbage, or an organisation formed to conserve heritage.
Ultimately society itself makes the decisions on what is important to society at any given time in its existence. As a body, society can make its wishes felt in many ways, and those wishes are reflected in the nature of a society's organisations.
With the Met, it may not be as simple as an insufficiency of funds linked directly to taxation, but the money trail will be there somewhere, even if it is not immediately obvious, and that money trail will be linked to the attitudes, standards and desires of the community that permits the Met to exist.