Forced charity is an oxymoron. What you're talking about is socialism, which is not charity (at least, when practised at a scale above that of a family or voluntary commune).
Yes, I know. I thought my meaning was obvious, but I'll be clearer: "Forcing" people to provide an alternative to charity is simply called "taxation" (to the extent that taxes are spent on things whose benefits are not distributed in proportion to taxation).
My point was that I don't understand your claim that you don't follow the GP comment's point, since you're surely aware that taxation and gov't spending are well within the Overton Window.
Yes, this is a pretty common position: govt charity funded by taxes is precisely forced charity, which many people are in favor of (myself included).