Marcus is the only HM to stand up to Lisa and Crew
 

That is why he must stay......Lisa will have them running scared if Marcus goes.....Freddie can't survive alone....marcus can!

I think you underestimate Freddie. If he survives another eviction (#5?), he will have a very strong position to fight from. He knows he is a very popular housemate. No one will want to go up against Freddie for eviction.

Lisa is not the one to worry about. Bea will be out for his blood as Freddie and Siavash are the last threats to her dominating the house. Lisa is more than happy to sit back and watch the bullying of Freddie as it satisfies her malicious streak and keeps her image clean to the public, in her eyes.

Little does Lisa know, once the main threats are out the way, she is next on Beas hit list!