I don't know about the legal side but if this is legal, it's pretty much a no-brainer for the company.
Assume that candidate A asks $90k and candidate B asks $80k. Let's also assume that each employee brings an equal amount of value to the company, let's say $100k. So, the company makes 100% more profit off of employee B even though they are paying only 11% less.
The whole "golf friends" thing doesn't make sense to me. I go to play golf to play golf, not find friends there. That seems to be unpopular opinion, but seriously, why do we mix those things up?
My point being, why do we do bother to do anything with friends? If you're going to do something, whether it be work or play golf, isn't it better with friends than with strangers?
Extended nitpick: Technically, they only said "then add 20%". They didn't specify of what that 20% is. It's up to interpretation whether they mean 20% of the original value or the doubled value.