IMHO, this is much better than giving an exercise for test. They are talking about 10 hours per week. So $1000 for four weekends (while keeping your existing job) is quite attractive for anyone trying to get entry into tech space.

I would imagine many (not from 'traditional' academic background, or fresh out of some unknown college, etc.) would do this for free for a decent shot at getting hired in a well known tech company.