@Ralf *********
well, it is not the same for both, as a 1-year extension on a Non-O family visa is always issued for 4 weeks "under consideration", and Immigration will conduct a home visit to him and his wife within this period.
So this must definitely be communicated with his Immigration office if he intends to apply before he travels.
If he stays in Thailand after he came back from the trip abroad and after he submitted the application, he need not worry as he will be present at home when they conduct the visit