Straddle L Sit Question

In BtGB students are encouraged not to sit on their legs. Does this mean that one shouldn't touch at all, or that one is resisting the contact and trying to lighten it?

From the photos it looks like they are somewhat sitting on the legs, but with strongly engaged abs.

its fine for your legs to touch, the key is that your hip muscles should be fully activated. It is possible to cheat by using the arms to hold the legs in the straddle without using the necessary muscles in the thighs and pelvis.