It is illogical to make any link between the aircraft part and a suitcase. There will be very few 777 parts floating in the Indian Ocean and so if the finding is confirmed there is a high probability it belongs to MH370. Suitcases - not nearly so unusual.
When finding any flotsam in the same area it may be tempting to link them, and if this was still mere days from the accident there may be some justification for that. But after all this time there is none.