If the deceased brother wanted to make sure his siblings got some of his assets, or some family heirlooms, or things of sentimental value, he should have had a Will. He may well have known that, without a Will, his son would get it all, and he was fine with that.
Deaths in a family often bring out greed, and resentments, even when there are Wills and trusts, which is why people should give some thought to estate planning, and make their wishes known regarding bequests, and have these formalized in legal documents like Wills and trusts.
Also, the brother of the OP only died two weeks ago. No one should be removing any of the assets yet--the estate has to go through probate, debts have to be paid, etc. The deceased person's son is acting appropriately by preserving the estate and by not letting anyone make off with anything at this point.
Also, if other relatives descend like vultures, the son may be less likely to give them family heirlooms, or things of sentimental value, at a later date. Everything seems to belong to him now, and, if they want something from him, they should go about it differently.