He is an intruder, you can bet he was sent in with a plan of attack and given prior knowledge of the housemates and who they (BB) wanted him to target. Thats why I think they put Lisa in with him, because they knew she would pass on biased information. It wouldnt have the same impact if they had have put Jason in with him, for the meet and greet, he would have probably held back from any harsh comments, they know that Lisa can't help herself.
They know that traditionally intruders dont last long, unless they have special talents and people skills like Zach 2007. I think Leo might have sussed out that Jason can be useful to him. To be honest, I wouldnt trust any intruder that said they had never seen BB and dont own a TV. Most people are walking around with a virtual TV on their phone.