When I choke a sound, if I do so right after the hit, choke works great. However, if I wait further into the tail, the choke does not cut off the sound.
I haven’t tested your observations yet, but I think this behavior is more or less what I would expect, regarding how the choking is implemented.
Choking introduces a low pass filter that dampens high frequencies first. The higher the velocity of the choke the more high frequencies the filter cuts off - lowering the cutoff frequency. As the cymbal decays, high frequencies are slowly vanishing and leaving only low frequencies at the very end of the sound. That’s probably why the effect is much less pronounced, when you choke an already decayed cymbal. You might get a better effect when you increase the velocity of the choke or make the choke note longer.
I would assume that this is similar to the behavior of a real cymbal: lower frequencies are a bit harder to choke and stay longer in the vibrating body - you need to grab it harder to make low frequencies decay.