I'd buy that we don't have great _evidence_ of its harvesting before that, which seems more like what the article says? But that's not really the same thing at all.
Seems like a fairly complex tech to pass on without some fairly involved language?
I wonder sometimes if we could teach them to make bread or baked plantains or something, idk, and then have that habit passed on to their offspring.
The sticking point could be fire, seems rather hard to make, and even worse - maintain, without all the convenient tools we have today.
They imitate the behavior, and you can easily find some pretty cool pictures of it. However, I'm not sure an orangutan has ever actually caught a fish that way.