Contractors aren't going to get up to speed any faster than internal resources (sans technology specifics like expertise in a language).
Depends. If he is talking about things like HFT (sub-ms speed and paranoia of employer to share sourcecode), you can get contractors with a lot more that just expertise in language - they know exactly what to code from start till the end, what are common stumbling blocks etc. It is just getting a person to write a http web server, in some alternate world when there are no open source projects and no reliable 3rd part providers. Getting a contractor which has already written 5 web servers for different companies is going to speed you up really a lot.
Such dynamic is not common in other areas - but in other areas, being few % faster than competitor does not let you earn order of magnitude more money. There is huge negative incentive for companies to share their code and no incentive for contractors to spread/share their knowledge in form of open source, as it can directly cuts into their future profits.
Said that, it might something else, because:
- for amount of money you are paid (we are talking 1000+ daily, in whatever currency you happen to like), people are generally willing to relocate, especially for shorter projects, which this one seems to be
- HFT is not exactly a hot subject right now (and they might be already reasonable off-the-shelf solutions, I'm outside of that for some years now)