Yeah, and a bloodhound only needs one sniff of a t-shirt to find a kid.
I'm sure there is something that could be useful that was missed, but speed is also important. How quickly do idiots in terrorist cells in California go to ground? I don't know. But I'll bet it's better to go after them today than in a few days. If nothing vectors toward them in the intervening period, I'm sure some folks here would say they didn't act fast enough.
Rule No. 14: There is no satisfying most of the INGO membership most of the time.
I think you're confusing the investigators being done for now after giving the place a quick once-over before getting on to other things with the investigators being done completely with no need to ever go back for more evidence.