Why is it necessary for Scripture to say anything about it? It makes sense to do so.
The notion that the blessed in Heaven are inert and powerless (unlike ourselves) and have no desire or ability to exercise charity toward the living flies in the face of common sense.
Their doing so detracts from the glory due to God precisely as much as your feeding dinner to your children is an insult to God.
Or, is this what you believe: “You don’t trust God to feed your children, so you do it yourself!”
Acts 17:11 These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.
“But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.” Galatians 1:8-9