I think the difference was that Julianne and Lubov already had plans to compete and had costumes and other things made. Both partners had the entire competitive season planned out and Charlie led both of them on to think he was still intentionally competing with her. There's a major difference between that situation and this one. For one, we all know what a competitive season looks like. It's set, it's scheduled years ahead of time, and there are competitions one does.
Here, there were no open or active working schedule Duhamel and Radford were on. Like I said, if there were actual shows they were contracted to partake in OR if there was such thing as a professional schedule and Radford led Duhamel on only to blindside her with the James partnership, then I'd find him totally at fault. There are no shows, months have passed up, and Radford found an opportunity to compete with another partner. He could have been more considerate, but we know Duhamel was not planning on competing again nor did she make plans or prepare for a competitive season only to be left high and dry. She was at home with nothing on the horizon.