Here's the thing: they don't need a better argument. They don't need an argument at all. It's their preference.
> I don't understand it fully. It doesn't seem morally justifiable to me, and they encroach more on the professional autonomy on the remote worker than the remote worker does to them.
Here's the thing: it doesn't need to be morally justifiable to you or anyone else. It's a preference for working in-office with other people in-office.
I think you do understand this it's just that you don't like it because you have your own preference.