The way I'm interpreting this, it's not _because_ they used a personal address, but rather that they weren't allowed to contribute to VNIC [for contractual reasons], and using a personal email address does not magically bypass that restriction.
(The current title is "IBM employee forced to stop kernel work for using personal email address", which is an interpretation likely missing context)
(The current title is "IBM employee forced to stop kernel work for using personal email address", which is an interpretation likely missing context)