Also: you say the field has comma-delimited values (2/7, 2/10, 2/20). Are you sure they aren't semicolon-delimited, since that's the way they're saved on form submit?
Ah, yep, I missed the requirement on allowing for multiple selections, so you are going to want to go down the path recommended by Dory/Sanford, since segments unfortunately won't be able to work around that.
I thank you for bringing it up because it helps demonstrate, like we were talking about in our local MUG the other week, how Velocity can pick up where segments leave off.
Yes, the reason I suggested velocity scripting and not segmentations with dynamic content is because there are many combinations of dates that a person might select, and you'd have to set something up for every single combination.
Otherwise, there really isn't anything native to Marketo that will help out here.