No, the gamma compression distorts high-frequency components that have close frequencies f1 and f2 into products such as the low-frequency f1-f2. The reason you don't see this low frequency on your screen is that the inverse gamma curve on your display undoes this distortion exactly. But if you remove the high frequencies f1 and f2 by downsampling before displaying, the only remaining signal is f1-f2, and because of the lack of high frequencies it isn't removed by the inverse gamma curve. So you're left with a visible low frequency signal.
And f1 and f2 don't need to be close to Nyquist, as long as they're significantly attenuated by the downsampling filter.
And f1 and f2 don't need to be close to Nyquist, as long as they're significantly attenuated by the downsampling filter.