It's easy to hide things from satellites. Or dispute what the blips on the ground are. And since "they" know when the satellites are overhead that makes it a bit less useful. (Note that the Russian Def Min "debunked" the US-provided satellites by stating when they would have been taken. Accurate or not, nobody came back with the response, "You can't know that!"
This kind of thing produces real-time continuous data on air movements of the other side's planes. So in Ukraine where Russia frequently intrudes on Ukrainian airspace, a satellite won't cut it. You want real-time radar data, and if the distance is too great you need to collect that data from the air so you can "peek" over the horizon a ways.
It's also good for picking up short range or directed communication. During the time involved there were troop movements all along the Russian western perimeter. (There still are. Troops moving to the Ukraine border along Russia and Belorus. Air units were redeployed.) You want spy *planes* to pick up what satellites can't. Moreover, spy planes often contain some processing ability so the data might be pre-processed before it's transmitted to HQ in a secure way.
Perhaps this was just dickwagging and Russia flexing its muscles, saying "This is international air space, that means it's Russian territory." Perhaps Russia didn't want the spy plane to see what was happening.
Plus it's possible that this involved Kaliningrad--you know, some of that historically Prussian-German territory annexed by Russia after the end of WWII as spoils of war. (The Prussians are extinct as an ethnicity, their language was mostly dead by 1700.) It's largely closed territory, even Russians have trouble visiting there, and Russia is really anxious about "separatist" and "federalist" movements on its territory. It views the Ukrainian Maidan as a trial run for Russia.
Kaliningrad is also a bone of contention because it's like Alaska with no land access from the rest of Russia. (Instead they have to go through the Baltics. Russian blockade of another country = just and right. Blockade of Russia by any country = act of war. Crush separatist movement in Chechnya through massive bombardment of civilians, good if it spares a Russian life. Crush separatist movement in Ukraine through much less massive bombardment, genocide if it kills "innocent Russians" in masks and camo manning Grad launchers. Understand the thinking.)
Not everything is Vietnam, 50 years ago. If you had any authority over what happened in Vietnam you're very likely to be in your 80s, at the least. Even an old ex-felon who was convicted of rape is allowed to put locks on his doors, and his children and grandchildren are certainly allowed to. We don't visit the sins of the fathers on the children unto the 10th generation.
Edit history
= new reply since forum marked as read