It was to try to gain a little insight, more than what was obvious. Applied the right way, you can see how it could be used to tell if someone was lying or not. But it's all useless without the opportunity.

[even though she could easily hold Subaru's hand, it's the conveyance of information that is the real difficulty. and anyway, listening to the conversations around them, things were getting more complex than interrogating one person should provide.]