If you want to keep your poll more private you can hide the guests from other guests and either let them just see the vote count for each date/time option or hide the vote count as well. Here are screenshots of how the guests see a poll that has a hidden guest list and a hidden vote count.
Guests see the vote count for each date/time option but not who has voted in the poll.
When the vote count is hidden the guest list is always hidden from other guests as well. Here the guest can only see his/her vote in the poll.