Seeing Dober, for Geo, was a big surprise. After defeating Athos, three Amra in total had led the race and their multiple planets and this included Dober himself. Although originally Dober wasn't a fighter, he had grown quite strong.
He was brought into the group due to his smarts and information he had on new technologies. Back then, he was one of the few Amra that was researching technologies that they could use.
However, being around Geo and Nock who had great power, had also somewhat influenced Dober. On top of that, he gained natural strength as he worked in the Forgery and helped around in several places in and outside of the tower.
This was why Geo was surprised in the first place, because Dober was in the tower, and if he was now out of it, there was a chance someone else was as well.