In ArchiMate you could model the concept of a Data Owner as a Business Actor, a Business Role, a Business Object, Data Object, or a combination of all of them. The 1st 3 are elements from the Business Layer while the later is from the Application layer. It all depends on your business requirement; for example are trying to capture a collection of names of people owning the data and the data they own or are you trying to describe the process.
For different types of data owners - e.g., Product Catalogue Data Owner, I will use specializations, probably even if I was not using ArchiMate. However, if you want to model the fact that somebody - e.g., Joe Smith - is the owner of the Product Catalogue, you probably need to use an instance and may not be able to use ArchiMate.
A point we discussed in thread you refer to is that ArchiMate is a featureless modelling language, it does support attributes or operations. Because it is featureless you cannot instantiate the way you will in, lets say, UML.