I doubt ATC made the mistake. They told the CG plane to hold short of the runway.I'm not knowledgeable about these procedures but apparently the Airbus was cleared for landing. Which leaves an incursion by the coast guard plane very likely, or the ATC made a mistake?
The CG plane crossed the runway, and was struck by the landing JAL.
My gut - echoed above - and supported by Juan Brown’s video - is 100% on the CG airplane making a terrible mistake.
One common thing I see from military pilots who transition to airline, is the lack of experience with crowded, high tempo airports, like O’Hare, or Haneda. I suspect that lack of familiarity will prove to be a factor in this case.