to assume that trade in silver drove the phoenicians is just foolish.
As you noted, lots of products were involved. In addition to buying, there was selling. It is likely that while trying to sell their stuff, the phonecians were offered silver and that did in fact did increase the trade with sardinia and the trading houses in spain
The sources of the silver is what the study was for, shows the silver source shifted west as the Phoenikes spread that way. I wonder if a similar approach would be fruitful to track the source of tin used to make ancient bronze over the centuries?