You are right. Helsinki/Espoo, Tampere or Oulu would have been far better choices from the point of recruitment but this is a large piece of land and probably Google didn't want to let it go.
Besides they must have thought the name Google is enough to get smart people where ever they want.
btw this is what centre of Hamina looks like : http://torikamera.haminetti.net/user/toricam.html