As always, the bonus for VIPs on their Birthdays should be different, and the email is for bonus promotion purposes only.
Why not have fun with the bonus it's ok to play these bonuses while celebrating his birthday, isn't it? If I were him I am going to play even a small portion of my deposit+bonus I may be hit a winning streak like what happened to my birthday a few months ago. Withdrawing it without playing will hit you bored.
You know sometimes in those emails they say 'no problem to buy beer and cake' yeah even though they want all users to keep gambling but they still remind to celebrate it

Plus he gets 2x bonus so he can take one of them for withdrawal. Don't forget that gambling only promises but does not guarantee that means you can't hope more for something that is uncertain, if you win on your last birthday bonus means you are lucky while I lost when I got the same bonus yeah of course our luck is different. By the way what is your VIP level?