I get why the places that do this charge $350+/-, that is painstaking work!
My curiosity was when he was filing down the worn inner links rather than adding material (laser welding) to repair them wouldn’t that make the links uneven as is tapers?
I expect the gold centre links may have worn a bit narrower as well, considering how worn the bracelet was. The taper of the bracelet may have ended up a tad narrower, but a small penalty to pay for salvaging a bracelet that would be expensive to replace.