The Sparkpeople Community Guidelines state:
"No UGC images that might be considered "inappropriate". For example, we do not allow pictures that are sexually explicit/suggestive, too revealing, pictures in undergarments, or anything else our staff determines is not appropriate for the site. In general, we consider our site to be "PG-rated". If you are trying to take pictures that clearly show your weight loss progress, we recommend tight-fitting clothing (such as spandex) so that you can still see changes easily."
(UGC is User Generated Content). Note undies are not okay, so I would suspect bikini probably not either. Yes, there are heaps of photos that breach this. Feel free to report them as you find them. :)
Deb, in New Zealand