Actually, if the house was held in joint tenancy, which would be most likely, a joint tenant cannot kill the other joint tenant and end up with his/her interest in the property.
You are correct in that Scott cannot end up with Laci's half of all the assets.
I see you live in Calif. and you probably know that Calif is a Community Property state. As such half of all the assets acquired during the marriage belong to Scott. (except gifts given to a specific person) He would not be profiting as half of the estate is already his. The house would be no different than a savings account, checking account, etc. Sad as it is they cannot take his half from him. He will need it all to pay the lawyers.
Now if he were to have bought a life insurance policy (which I think he did) he will not be able to collect on that for having killed Laci. And hopefully he will not be able to profit from any book or movie deals.
Also say if Laci had made out a Will giving Scott all her half after her death, I am sure that Will would be made null and void because then he would be profiting from her death from murdering her.