o when you deploy ships you shouldn't be revealing your speed immediately, or you're also giving your opponent info about your maneuvering! This "loophole" during deployment lets your opponent go "Oh, if your going to do that (changes his or her speed dial) then I'm going to do that"! The whole idea is absolutely ridiculous, once again, because neither of you can do it at any other time throughout the game.
Steiner
Unless you use a Navigate command to change your speed - something that is seen regularly enough to not be surprising, and something that I'd argue Admiral Ozzel is primarily based around (surprising speed changes overall, not just during deployment - but using him to immediately significantly change all your ships speeds is a now well-known strategy.)
Several things allow your to adjust your plans based on your opponent's actions such as liaisons, Support Officer, and other dial-fixers/token granters. The ability to set one ships speed based on the knowledge of one opponent's ship's speed is not a hugely significant departure from that, or from the general idea that second player gets some advantages overall. Deploying first is a cost of getting to activate first. Revealing your speed dial is a part of that cost.
I would argue that the justification for allowing secret speed-dial deployment is thin enough that almost any TO will rule against it, especially since no rule says that you can do it (and the rules are clear that you can only do what is expressly allowed) so I doubt you'd be able to "sort of cheat", but I'm not sure why you'd want to anyway.
As far as fluff considerations about ships accelerating, Star Wars sensors can determine engine power output, so they would be able to determine at what speed enemy ships are traveling. Plus, of course, this is a game, so trying to hold it to strict laws of reality is a wasted effort, it uses rules to be a fun game to play, not to mirror reality as perfectly as possible.