I understand what you’re saying, but the crash site didn’t strike me as strategic military ground, so I didn’t see what the purpose is in mining it.
Ukraine army was pinned down there at the time of the crash....I suspect they want to retain any ground they gain...so mining the area shouldn’t surprise any.
Further, how would any of us armchair folks really know what’s happening on the ground? Propaganda is so thick you can’t cut it with a knife now.
Given that there's nothing left to loot I agree unless they're afraid someone would cart parts of the aircraft off to sell as scrap. Since I doubt there's much of a market in the present circumstances, the chance of that seems to be between slim to none.