Yeah, like I told Sean, you're right in the case of non-humans at a distance. In the case of humans, either the sound of the bullet will come from a "line" in space seemingly at the same time and with the same intensity for a very small timespan, thus making detection unlikely or they will be close enough that the coils and the charging and the discharging and all that will be audible. You'd have to be in some sort of sweet spot where you're far enough away to not hear the gun but close enough to hear the bullet.
But, like you said, there's no reason not to do it, since it doesn't cost anything. Plus, maybe simply lowering the power pumped through the gun will lower the noise it makes, which I hadn't considered until right now. So yeah, it's a very good idea,
Irrelevant to the discussion since I already agree with you, but there's one detail I don't like in those experimental data. It says it was 32 metres down range from a suppressed rifle. Now, again, I haven't actually done any measurements with suppressed and unsuppressed rifles, but it might have been close enough for the rifle to affect the measurement. Now, I don't know if they took any extra precautions like putting the gun in a soundproof box or putting some sort of obstacle like a hill between the gun and the measurement device, but if they didn't then that data is not completely right, since the increase in noise might be in part because of the gun and the larger amount of gunpowder used to propel the bullet and not the bullet itself.