Well, they are questioning the motivation to question the motivation of others. Assuming that this invalidates their point would, however, be a logical fallacy. https://en.m.wikipedia.org/wiki/Tu_quoque

Except that they are not questioning that motivation at all - blanket assertion that the activity is done too much but nothing supposed about anyone's reasons or whyfores.

I think that statement is being incorrectly reduced/interpreted to 'mind your own business' which would be ironic.