It's like negotiating with the mafia, you might get something out of it but if you cross the line you'll end up face down in a ditch and authorities will look the other way. Megacorps have stolen, copied, reverse engineered, replicated, etc. things since forever and it always worked out for them.
In this case MS didn't need any help. They could very well take everything and face no real repercussions (this is the reality when the majority is uneducated, and their elected representatives are greedy and spineless). So playing along gives some chance to get something positive out of it.