Soldat's own scrambling makes Idia jump back as well, not ready for that sudden movement so close to him as he instinctively brought his fists up in front of his chest, as if to protect himself. It's not threatening, it's very much defensive.

Then realizing what was happening.

Oh, wait, maybe he should had asked first. Whoops. "I-I-I was curious about your, ah, your arm." He relaxing one fist enough to point a shaky finger at it. "It's my computer, it was doing a scan to see how it operates."