I would have sent Menshov because two fourth places in the GP is pretty good and he should have a respectable skate at Euros, but I am a little surprised at the outpouring of emotion over this. It's not like Menshov had a brilliant skate at Nationals whatsoever. As Marco says, Voronov and Menshov are all about jumps, and presumably whoever outjumps the other will place higher at Euros. If they both had skated well at Nats, I guess they would be sent to Euros, so that the stronger one can be sent to Worlds and hopefully land all his jumps and eke out a 10th place. That's the best you could expect from either of them and they would have to be squeaky clean to do it.
However, if Menshov skates at Worlds as he did in Nationals or the GP, there is very little chance of him making the top 10 at Worlds, so there is little point in sending him from the fed's POV.