Daia's going to make no effort to stop her touching the goop because, uh, he's no expert either. And since Kumoko is leading this part of the mission, he definitely trusts her way more than himself. And the lack of effect as she touches it seems to prove that to be just fine.

He looks at the jars, hesitating a second. But with the mental reassurance that this is fine, he goes ahead and picks up another jar, twisting to get the lid off. Though he'll hold this one a little further away from himself this time, just in case it wants to drip, too.