Actually, as far as I can see, that launch date is for their official attempt. Meaning, they'll either carry more than one person, or ballast to stand in for the others. So June 21st will see their first flight, with a follow-up within the 14 days after that. Meaning by mid-July, the XPrize shall hopefully have been won.
Regarding safety: Theirs is an experimental craft. It is designed for test pilots, with the same risk level in mind. I have no worries whatsoever that it is safe enough for that use - not for commercialization, maybe, but that is not what they are aiming for. Should still be lots safer than the shuttle.
Of course it furthers space tourism. It demonstrates that privately funded, low-cost space programmes are feasible, and it will increase investor confidence. That is the main aim. Besides, the other XPrize contestants plan to commercialize their projects (as does a company that involves Burt Rutan's brother), so within the next 2-5 years, there will be a second programme to offer space tourists: $102,000 for a few minutes in space (some aim for 3-5 minutes, others aim for 20 minutes or more, though not for the XPrize), as well as the $20,000,000 for a week on the ISS. That is already one small step ahead for space tourism. Once that turns out to be profitable, the company with the biggest commercial muscle may well develop a safer, more feasible, more commercial and cheaper (in terms of per-flight cost) space programme than governments, and that would be great progress indeed.