Gould: Oracle to Red Hat: It's Not Your Father's Linux Market Anymore

"1) "enterprise Linux" is perceived and treated by customers as if it were proprietary software"

If that's what the author wanted to say he should have said it in so many words. Said that way no one is interested since this isn't news (or even insightful). It's still flamebait because being treated as proprietary by some customers does not make RHEL proprietary.

"2) it is entirely possibe to "add value" to a piece of Free Software that effectively locks in customers"

Until the GPL'd patch is merged in to your competitor's distribution. If Oracle patches are not merged into RHEL or even mainline then they're optimizations that most people don't want. You could say that Oracle will keep making changes to the kernel that will always be rejected from mainline for one reason or another and that improve the performance of their DB, but if customers start leaving Red Hat because of this you can bet that RH will produce an Oraclized kernel in short order.

Vendor lock in only happens with GPL'd software when there isn't enough market for a competitor.