Right, but you can calculate distance based on the strength of the returning wave signal. Anti-radar materials deflect waves in a way that doesn't reflect it back at the station, or reduces your cross-section so that radar can't track you. Reducing your profile size to that of a vulture will draw some WTF glances because birds don't fly that high. Ultrasound has very good resolutions as well, so at shorter distances you would look like an anomaly, not a cat.
And that's my point. A wave loses strength over distance, so a "vulture signature" at 10 km might not even be reflected with strength enough for the radar station to pick it up in the first place.
The same would work for ultra-sound vision, you would either reflect it back with a lower signature (which wouldn't give you a cat-like shape, but it would reduce it greatly, thus a "cat-size signature") or you wouldn't echo it at all.
Now, is ultra-sound vision supposed to work like Marvel's Daredevil vision? With that kind of resolution? Because if it is that advancedm then yeah, at closer ranges a sound-absorbing suit wouldn't help you at all, but a greater distances, yeah, I think it would be fine.