Your brother is an individual and saying you think he should interact with you when you please and that is an option/choice that "shouldn't be taken from you" is not very considerate. I know in my family if we want space we say so, and if we don't want to do something together we say so. It is a matter of respect. Of course if that family member was showing concerning signs of depression, etc. We'd politely try to talk to them.. but if he doesn't want to talk for a few days just give him space to sort things out. Anyway you sound rather young so it's to be expected that something like this may be upsetting to you.