Nothing wrong with red/green, nicely captured.
Beautiful image, your exposure looks very good
By definition, RAW data should always be what the Red, Green and Blue sensors 'saw', the issue is whether the camera tells RAW Sony Express it was shot in monochrome and then how RAW Sony Express displays it.
I have absolutely no experience with Sony DSLRs or RAW Sony Express, so I cannot be specific.
There might be a checkbox somewhere in RAW Sony Express configuration options which enable it to follow the meta data sent by the camera - and hence display it in monochrome (automatically).
That's assuming the camera actually does actually set the meta data in a RAW file to monochrome.
It is also possible that the camera's "B&W" setting may only apply to the jpg files generated.
Hope that de-mystifies it.
Cheers, Dave
Nice image, I like it. The fruit reminds me of my managers hair ......minus the red.
Dave