"It is more that some Sith of the past refuse to leave even in death. I'm sure the echos of what remained of them is what infected him."

And as far as he knows the man and his followers stayed inside the tomb and probably died there. It wasn't as though there was anything in there to really sustain them.

Malgus himself walked up to the throne and sat down on it, reminiscing slightly over his failed attempt to usurp the entire dark council. Though his plan ultimately failed, he did manage to incite some change though it doesn't seem that it lasted over the years.

"I only briefly sat at this Council. Sith politics left much to be desired. So much arguing and disagreeing."