I do not understand the rationals for this, its licensed under GPL2, care to elaborate a bit ?

Parts are licensed under GPLv2+Classpath and other components like the js / python layers are licensed under UPL. And based on https://www.graalvm.org/downloads/, it would seem that Mac use is only supported by their "enterprise edition"

"The reason why we don't build CE on Mac OS is purely technical. Its because there was no OpenJDK 8 build for Mac that we could use. We hope we can change that soon. OpenJDK builds got a lot more regular with Java version >= 10."

(Source: https://news.ycombinator.com/item?id=16859559)

GPL2 doesn't give a patent grant does it? If not then you could still potentially be sued for patent infringement.

I thought GPL2 had some protections for that?

http://en.swpat.org/wiki/GPLv2_and_patents

https://github.com/oracle/graal/blob/master/regex/LICENSE.GP...

I'm sure Oracle has figured out something to screw you over once GraalVM becomes popular.

nit: s/rationals/rationales/