The actual mechanics of how Beastmen temper individuals without the actual Primal present are never explained in detail, but it's undeniable that this is something they can do. In the case of the guards, it is likely that these people have been tempered for a long, long time, and have been hiding their loyalties so they could infiltrate. The tempering of the guards was likely NOT done after the Qalyana's "diplomatic" party arrived, but well before.