Excellent questions! He's basically got "Protoss Shaped" bends in his legs.
The answer, in short, is "contextual bullshit". Basically, whatever cover story I happen to be using, or we happen to be using, for whatever we're doing in that area.
Digigrade legs aren't Restricted, though Raptor Feet are, so it is more of a matter of having a plausible reason to have them. If we need to hide the fact that I have them, then an ARO could be used to disguise them. If we don't HAVE to hide them, then the reasoning could be many different things. Private security, bodyguard, former athlete, are all valid reasons.
I was considering a Fake SIN for an "armed courier". Basically, he has them to move faster, and Raptor feet to protect himself better.
I mean, yeah, he sticks out a bit more than others, but really, it IS the Sixth World. People get cyberware and bioware as fashion statements. As long as I have a decent excuse, I'll mostly fly under the radar, but it does depend on the context of what we're up to at a particular time.