i can see where you are coming from. at the same time if the person mentioned they are leaving forever, then it would be a appropriate time to ask for the gold politely. better than it going to waste.
when i quit the game in the old days, i think it was BFA. i assumed it would be forever and i donated my gold to Brigante since we were both on Argent Dawn.
Getting tired of wow - Community / General Discussion - World of Warcraft Forums (blizzard.com)
I came back eventually, but i assumed i would not. i mean dont blame me BFA followed by Shadowlands looked like it was the end of wow. what brought me back is the customizations + friends