Agree but given the size of a search area it is unlikely to have been covered, particularly by towed array which also leads into my other query “Why was the ship outside the search area and if it was transiting would it not be quicker to do so without a towed array or can it detect without a towed array.”
Not only that, the odds of it stumbling upon the beacon are very low. With detection ranges of only a few kilometers, only from a deep towed listener, it takes a very long time to cover a wide area.
I suppose they might have found debris using a side looking mapping sonar, but again, pretty unlikely.
Either the Chinese are extremely lucky, have undisclosed but very good intelligence as to the sunken wreckage location (not just surface wreckage), or are wrong about the report.
BTW... after 30 days, the beacon output is supposed to be down only 3 dB (half power).