seriously, you're missing the point. He's a computer scientist, asking if he can place a server on site to pick up latencies. If this is the case, he's most likely setting up strategies via an API, and could do better - maybe 50% of the time he could do better - if someone didn't beat him to the punch, that "person" probably another automated trader.
So, to say the the Canadian Dollar CME future is plenty deep and liquid might be true in a low volume world, if he really wants that type of speed - from API to broker to "Destination" and back - CME currency futures are in no way the bastion of speed OR liquidity, and certainly not a combination of both.
Your point is well taken that globex is liquid, and your assumptions the original poster isn't high volume is a bit off - if hes coming through an API, and looking for speed, a few of us here said that that's probably not the best place to do FX.
You have to understand that most if not all people coming through an API and asking for speed would also need a good depth of book and liquidity. Otherwise, well, if he's writing a program to basically be a market maker - or mean reversion, or trends, it would be necessary under all three strategies - to have more than just a few people in those pits or on the Globex screens. Outside of maybe 4 or 5 major currencies, those pits and screens are thin.
What you are arguing is that some broker thinks the currency futures are plenty thick enough for this guy. They may not be, and your brokerage may not be the answer, either. Consider the two or three people telling this guy to look elsewhere - for product and/or service/broker - aren't giving bad advice.