When it comes to questions like, "Can Kaioshin be sensed?", I feel as though it's best to go with what the story was trying to convey. Every statement made about them seems to be based on intuition. The fact that they were different would raise some alarms, so that's probably why Goku and Gohan thought they were strong.
The moment Goku wakes up, he begins to sense everything around him. I can understand not sensing Gohan, but I find it hard to believe he wouldn't have sensed Kaioshin in a weakened state if he actually had Chi to be sensed. If Goku can sense weak ass Bobbidi's Chi disappear, then sensing Kaioshin would've been likely if he could be sensed. Kibito can sense Kaioshin simply because they're of the same nature. This explains why Old Kaioshin was able to gauge KibitoKai's power later without any issue. They're the exception here.
After Goku goes back to Otherworld, he quickly sensed Gohan on the Kaioshin world. Once he teleported there, he was shocked to see both Kaioshin and Kibito there. That tells me he couldn't sense them, or he would've at least had an indication of them before getting there.
Kaioshin and Kibito merge, celebrating their new power. Goku just looked at them and said "weird" while continuing to give them a strange look the entire time. Power is often the most important thing in the series. The fact that he didn't comment on his power once tells me that he didn't sense him. The only one who could was Old Kaioshin.
I can understand not being able to sense someone because they're not fighting, but that's entirely different than being suppressed all the time. They have no reason to be suppressed like that outside of the tournament since their identity was no longer a secret.
Honestly, I just don't think they can be sensed. Too many things show that they can't.
