We all appreciate open source wallets, they are the best around but have we ever thought that being closed source is security? If Binance Trust wallet could be a closed source maybe they did this because they don't want malicious people to find out how they run things which could make their wallet become a target?
If you can't see how things are running (coding) wouldn't that make it harder to attack such code or network?
open source says > see this is how we run things, we are transparent and we have nothing to hide
Closed source says > we don't want you to see how we run the codes, you can target us or something
It's easier to make a phishing/scam copy of an open-source wallet than a closed-source one, but if people are financially motivated enough (like NK's Lazarus Group) then they will go out of their way to make a scam clone of the closed-source wallet as well.