The weird thing about this is that he doesn't seem to have been doing anything other than his job and that job doesn't involve anything that would be controversial as far as China is concerned. Nor is there anything I can think of that that Xi might want him to do that would require him to subvert his authority. Even if this is somehow corruption-related from his previous job, you'd think that the Chinese would be savvy enuf to realize this wasn't the best way to handle it PR-wise. At the very least, wait until both he and his wife are in the country to disappear them.
Clearly, Xi does not want Interpol meddling in China's affairs, and this is an attempt to send a message to them.
He could've easily detained a foreign national who also was a member of Interpol instead.