I think they want to test against Russian air defence, and they want to use Ukrainian pilots, since none of them is likely to survive.
It is just more sick, cowardly exploitation of Ukrainians, and sending more of them to their deaths.
That is highly unlikely. Think about it. These will be 30-40 year old F-16s with long obsolete jammers and etc. And SEAD (suppression of enemy air defense) is not just some fighters flying over with HARM, its a complex multilayered system. There is nothing to test.
There is no way such missions would have any value in evaluating Russian capabilities vs current USAF SEAD.
What you say makes sense as I agree with the Operative that the F16’s aren’t about to approach the line of contact, but the test will be when the F16s are several hundred miles to the east and the Russians fire off their S400s. The S400 travel at 3 miles per second, so in about 100 seconds, they’ll go 300 miles (500 clicks, as we say in military lingo). The question is whether the F16s can make it to the ground and somehow protected from the S400 ready to run up their Afterburner Butt, in under 2 minutes.
I guess we’ll find out.