When my 2 year old was missing for 30 minutes... (in just a diaper) I first quickly secured her 3 year old sister so that I knew she was not going anywhere.
I knew my 2 year old was not very far, I had only been in the other room for a couple of minutes when she got outside.
Then I ran around frantically but systematically looking for her (most dangerous places first.) WITH my cell phone, calling family members (who were within 5 minutes away) to come help. My teenage brother was "stationed" at the driveway to ensure that she wasn't up or down the street and that she didn't come down the driveway.
If I had NOT had my cell phone or if I had NOT been in cell phone range...there is NO WAY that I would have stayed in the house calling anyone, rather than been outside looking!
I knew that she was very close, wasting time calling without looking only would have allowed more time to pass. I was 99.9% sure she hadn't made it off our 1 acre property. I had already decided that once I had 5 people helping me, if we didn't find her in 5 minutes, we were calling 911. I found her just as everyone else drove up. In between the horse pasture and ditch, next to the road behind a huge shrub.
Now, if I had been in Sylar's situation...
If the cell phone reception is bad there and you can't run around on the phone, I would have absolutely had my teenage brother call for me.
If there is no cell phone reception and you have to go find the camp host to call for you, I absolutely would have had my teenage brother call for me.
If my brother's teenage friend was an option that would be even better, because I would prefer my brother be helping me look...as my daughter would be more likely to respond to him than to his friend.
If they really believed Sylar had just wandered out of the tent a few minutes before...and was very close by.... having the unrelated teenager call while everyone else searches makes sense to me. They would not have wanted to stop searching, when they had someone else who could make the call for them.
Then again, I tend to see things differently than most.