If the UAS is capable of conducting surveillance, then it can assist with SAR. Atleast it can help with the search. Personally I think it sounds great to have an asset with Day video/FLIR and 16 hours of flight time conduct search patterns looking for survivors. Then call the manned helo once you have an accurate Lat/Long for the survivors. Cheaper, safer and gets the job done.
Well, we do have an asset like that, called the C-130 (OK, 14 hrs of flight time), however, video/FLIR is used more as an identification tool than a detection tool on the Herc. I'm guessing at the speeds they fly, and with their camera package on board they might have a better time detecting something, however sending it to find a small object, like a raft or overturned boat may be trying to ask of it something that the sensor suite wasn't designed for.
As Coasties know, doing more with less and using something beyond what it was originally designed for is standard ops in the CG.
Of course, use of this as a SAR asset involves a different pot of money (every flight hour gets charged to someone), and with limited hours they wouldn't simply throw this asset into a SAR response without some deep discussions waaaay above my paygrade.