Legally, these things are usually done either with patent law, in which case it doesn't matter what the employee does but what the company does, or as violating

Legally, these things are usually done either with patent law, in which case it doesn't matter what the employee does but what the company does, or as violating terms of employment, in which case it's not really an IP law being violated but contract law. This is where noncompete agreements and the like enter into the picture. Really it's a mess, because of course you are going to take your experience and knowledge with you. Bottom line, those employees are finally free of ASML after the legal settlement with the XTAL lawsuit, and have no contract with them that they can be accused of violating, and so they can go work for whomever they want. If the new employer violates an ASML patent, then ASML can go after the employer like anyone else. But who these employees work for isn't ASML's concern anymore.