Sol was not the only one taken aback by the familiar situation in the underworld, they had also expected to find one hellish place that it would be hard to survive in.
It took them a while to went out of their daze and regain their sense, Sol directly conjures an armor of ice to protect himself from any potential danger.
Even though the environment did not seems dangerous, the appearance was often time different than reality.
Sol had been told by Nerodia to not underestimate the underworld, it might not look dangerous but even a random creature in there was at least a demigod.
"So this is why she told me that it might look safe, this place really doesn't look like hell" Sol thought to himself.
When the other looked at him conjuring an armor, the follow suit, his action might indicate there is a danger nearby that only Sol can sense.
Of course they also on guard against him, Sol was ready for a fight, he could attack them any moment if they were unprepared.