Oxford Dictionary defines charity as the “Help or money given voluntarily to those in need.” Clearly the issue comes down to whose money is given and is it given voluntarily? When a government provides money to help those in need is it their money to give and is it given voluntarily?
Depending first on who you believe has the greatest right to the currency in question you could suppose it is taken from the private citizen so that it becomes the governments money. But for the later condition does the government provide it voluntarily? I can think of no case where that is true. It may come without condition, but the Congress controls how funds are to be used; no one empowered to just give away the governments money so the idea of voluntary disbursement seems a non-starter.
For this reason I believe anyone who says the Government can be charitable defines charity different than I do.