Good episode last night, and I have a theory:
Helo is a Cylone.
Here are the two most compelling reasons to believe that:
#1 - He saved the Cylones by killing those in containment before they could be used to exterminate the race, and did it without coming into contact with them.
#2 - When everyone was released from Quarantine except Sharon Helo knew that humans were not suseptable to the sickness, yet he stayed outside of the quarentine area rather then go inside to comfort Sharon, he did this because he didn't know if Sharon was infected and thus he could have been exposed to the disease.