As a heads up, that's an explicitly Catholic journal on medical ethics. It's also a fairly low impact journal. The first author is also a nutritionist and the second is an explicitly Catholic ethicist. The fact that they define personhood that way should neither be surprising nor taken as representative of any broader view in human development.
There is nothing in the guidelines for authors that states that the authors must be explicitly Catholic. What's more, they are a member of COPE.