Health, your mistake is conflating two issues.
The container with holes in it is not separating any mixture. The only thing to even talk about is that it holds back the solids and allows the liquid to escape, but it’s not truly considered a mixture, as I mentioned (see ‘??”? ??”? ??”? ?).
The other issue is the dirt mixed in with the fruit (in this case the cherry tomatoes). There is what to discuss (although many poskim are meikil, including R’ Shlomo Zalman and R’ Moshe, to wash fruit right before eating), but this has nothing to do with the holes whatsoever. I also don’t know if the pesticides qualify as p’soles.