They can easily buy it, if they're producing a AAA game they wouldn't worry about purchasing a license, but they're either promoting Crystal's engine or saving money.
There's a likely chance it could be the latter, some low-budget games have turned out better than the high-budget ones.
The only positive thing I saw was already discussed, the fact that they have experience in this language but someone pointed out that it won't be hard to learn another, but someone else disagrees.
Touché.
