You are right, the investigation brief says "any device" used needs to be handed over. I would imagine this has happened already, if the investigation indeed started July 1. He has already had plenty of time to delete stuff.
The story on facebook the other day made no sense and was clearly lies. So we are to believe he creates 6 or 7 activities in 1 day of varying distances, but only 1 or 2 of them don't upload that evening because of bad internet? .....hmmm....sure, those 20kb files must have overloaded things.
He should have google searched "can I manually delete activities from my TomTom". Few seconds later he may have realized that wasn't a great lie to tell.