-snip-
I think is not wise to give 5$ without any string at all and can withdraw it straight without using the fund, IMO just set-up the turnover 1x time. You also can gite a good feedback from that rather that these rules.
Although there is no string at all for the bonus, but I dont think players will try to withdraw it without playing because KYC is needed in order to open the banking/wallet menu to deposit/withdraw. As OP said as well, by letting people to withdraw it straight away, it will also give them a feedback for their withdrawal system. The bonus is also limited to 50 users only, so even if all people try to withdraw it straight away, they will only spend $250 but I'm pretty sure no one will do KYC to withdraw $5 so the most possible case is that people will try to play it first trying to make more with the $5 in order to make it worth for KYC.