Once you get a solid cross grip, I think the top guy would be wise to stay in a low 'combat base' posture like that rather than stand up in compromised posture and expose himself even more to sweeps. Also, I can see that position arising from guys trying to pass low in order to kill the DLR game, either by dropping into the windshield-wiper pass (and you thwarting it by not letting their knee get to the floor) or you threatening the cross grip triangle when they are on both knees (which some guys still do with some passes, especially at heavier weights), forcing them to put one knee up.
Seems reasonable -- thanks for your response.