Calling it a "race" is really strange. They're not trying to build the first supercomputer, they're trying to build the fastest/most powerful supercomputer.
For instance, let's say China gets theirs out first, but the US releases one several months later that is substantially more powerful. Did China win the "race"? Or did the US?
I don't think calling it a race is all that strange. It's perhaps more strange to talk about winning the race or beating another country though, as that implies some finality/conclusion to the endeavor.
This can be looked at as a continuous race to see who can build the highest-throughput computer, where the competitors' positions in the race are decided based on a well-defined set of benchmarks. The periodic updates don't indicate who's won -- they're just a snapshot of what everyone's positions are in the race around the time of publication. So it's more apt to say one competitor is ahead of another in the race, but talking about winning or beating someone maybe gets more clicks.
For instance, let's say China gets theirs out first, but the US releases one several months later that is substantially more powerful. Did China win the "race"? Or did the US?