You should be able to extract the code and use it in Pharo/Squeak without issue, even if it is GPL. What you can't do is include it in the distribution, since it isn't MIT. You also shouldn't study the code and write your own version of it - I believe that would be a derivative work, which would likely make it a GPL derivative.
However, if it was extracted, and you brought it in to do profiling, and then removed it afterwards, that shouldn't be an issue at all. Just remember to remove it after you no longer need it - that way the GPL code won't accidentally creep into the Pharo/Squeak code-base. Basically, this would be a great example of a project that should be an external project and not part of core (or dev). -Chris
