Considering the context, I wouldn't say this says much about the difference between Galu and Silver. Goku clearly wasn't expecting to just run into superhuman fighters all of a sudden outside the Tenkaichi Budokai with how surprised he was by Metallic's strength, so someone with superhuman speed intent on stealing from him would certainly be someone to make him put his guard up regardless of how much stronger Goku was. The theft is the context linking Goku's reaction in both translations rather than Silver's capabilities, being the most accurate way to take it.
Even if taking it as a strength statement in the anime, it's worth noting the anime portrays Silver as significantly more impressive than his manga self and Toei have been known to slightly alter statements to fit both their own continuity and later reveals (eg. Dr. Brief telling Goku his pod was in pieces when he found it to fit the filler of Piccolo destroying it or Trunks not referring to his Artificial Humans as #19 and #20 to avoid the anime doing the biggest retcon in the manga).
