Whatsapp allows desktop clients. I use it too. It is technically possible for someone to hijack this desktop client and do this without MBS's involvement, as long as MBS authorized that desktop. I think you need proximity, but you can have a computer near the prince, and that computer being remotely controlled by someone sitting far away.

Not saying this happened ... but there are many ways to blame it on prince and many ways to defend him (and blame a subordinate).