Modern science: Conclusion first, then we begin the hunt for evidence.
Horse pucky. You're all too ready to believe Mexico is the source. What they're saying is there's now reason to think the jadeite *may* have come from Indonesia, and that casts doubt (given the unlikely geography of the find) on Mexican origin.
We moderns are just beginning to understand the geological resources of Indonesia. That violently volcanic island chain could easily harbor unknown jadeite sources. I've seen many newly-discovered Indonesian gem materials just coming to market in the past 10 years. Who knows what "stone" age people discovered? We moderns are just beginning to look for them.
Consider that the source of Olmec "blue" jadeite was not re-discovered until the 1990s. But 2500 years ago the Olmecs knew very well it comes from the Motagua Valley in Guatemala -- although those weren't the names they used.
Let’s see now ... an island probably had fishermen ... and the fishermen had nets ... and the nets needed to be repaired ...