Nevada is the king of edge cases like this, and NV 655 is far from the only route that has only a tiny handful of shields, or only one shield. This one is a double whammy because it breaks the "one point per interchange" rule by having 1 mile of a route's length within what we'd otherwise consider an interchange. It's a signed route, so my interpretation is in line with Oscar's.
I will bring up NV 671 and NV 880, both of which are also in Washoe County, and are similar cases minus the 1PPI issue. Only 1 or 2 shields, one road it's on is completely unsigned, unsigned turn. In cases where signs are ambiguous, we defer to the logs, and the logs are pretty clear in all of these cases.