No, I'm not. Labor and capital mobility affect the extent to which more demand for labor is a positive for your putative Amazon worker, they do not affect the direction.
If we convert demand for two shop assistants into demand for one Amazon worker, that's actually NOT a benefit to the Amazon worker in any way, shape, or form, because supply of labor has increased as well. And that's assuming perfect mobility.
Now you can make big picture arguments about the improvements in efficiency ultimately leading to structural improvements for everyone overall -- that's Econ 101 -- but we've been doing a whole lot of that for the last 20 years and it's mostly making people in China better off and it's not at all clear that more factory jobs in China has positively affected the direction of demand for factory workers in the US.
But don't let facts get in the way of hand-waving theory.
Oh and your ground assumption is that Amazon fulfillment center workers want to be paid more for their jobs. No, they want different jobs. Creating more Amazon fulfillment center jobs at the cost of other jobs is not what they want.
