That's one definition. A word can have more than one definition.

Cambridge: "a person who has had a lot of experience of a particular activity"[1]

Merriam-Webster: "a person of long experience usually in some occupation or skill (such as politics or the arts)[2]

Oxford: "A person with long experience in a particular (non-military) position, field, or activity; any experienced or ageing person."[3]

Vocabulary.com: "Veteran commonly refers to someone who has fought in a war––think Veterans' Day, the Vietnam Veterans' Memorial––but, in fact, the word can mean anyone with experience in a particular field."[4]

I could go on. They used it correctly. 10 years is plenty of experience for this field to use the term veteran.

[1]: https://dictionary.cambridge.org/us/dictionary/english/veter...

[2]: https://www.merriam-webster.com/dictionary/veteran

[3]: https://www.oed.com/search/dictionary/?scope=Entries&q=veter...

[4]: https://www.vocabulary.com/dictionary/veteran