Yes, as stated, the Sony D50 can certainly take a digital input. As to working with the Focusrite, it'd need to be tested.
I'm not sure I'd go as far as saying the D50 has compatibility issues, or maybe it's the spin that I find troubling. The D50 requires a signal meeting the requirements of the s/pdif digital standard (not surprising as it is a sony-based standard -- sony/philips digital inter-face standard). The issue has been there are some A/D's that do not meet the specs of the s/pdif standard, so they are not working with the D50. I just find the seeming blame onto the D50 to be misplaced -- it is the other equipment that is failing to meet the standard, not the D50. (Although granted, things like the UA5 and the V3 came out before the 24bit spdif standard was completed and formalized, so yes, it was a bit hard to meet the standard at that point as it hadn't yet been finalized.)
Edit: Reading with a bit more attention to detail, I see the flag in the digital stream was already noted, so my post is a bit redundant. Anyway, just a lot of posts talking about the D50 not being very compatible, but the issue really is with the A/D equipment.