Is it possible to update free apps from another account?
Yes, the same principle applies. For Apple, it is a purchased product, though in one case the price was $0.
So it's not transferable from account to account. As a developer, I know one normal case that is: the app is free for one day. Then the app turns paid. If a user could transfer to another account, then it would be a problem for the dev since it may be transferred to anyone.