RE the timing for resuming the search.
I would guess (and it's only that) the main reason for the delay is due to arranging for the most appropriate equipment for the task. The actual search equipment used for the first search, though very good at what it was intended for, was not necessarily the best for that specific task. In the past couple of years (months even) several new submersibles have been developed that would be significantly more effective. The main problem is these vehicles are not just sitting around waiting for someone to call and book them. Once developed and available they very quickly get booked full time for research (usually academic) for years.
I would suggest that it has taken a great deal of negotiation (and money of course) to secure the appropriate equipment, and to do so for the length of time needed to complete a thorough and adequate search.
grizz