sure it is.. it's all under the sentiment of Macs not producing products with performance parity with PCs.. What's wrong with just using a high-end windows laptop for field? Is that gap in the laptop space that big that warrants dealing with two distinct platforms that do not work well together?
He's most likely using the laptop for capturing photos (possibly tethered capture), and doing post-processing on the PC. Post-processing is what requires high performance hardware. It's also likely that he already had the Macbook and didn't feel the need to replace it at the same time.
I'm in the same boat, as it turns out. I switched from macOS to Windows for post-processing this summer, but I still have my Macbook for image capture and driving a telescope in the field.
Because the laptop is what he keeps his life on, and the work station is just that, for doing heavy lifting work in Photoshop and Lightroom and video and whatever. I don't think he wants to move his life to Windows which is a bigger deal, just his work.