definitely implied...

>It wasn't just
>about saving Frank's life. It was saving his own.

Exactly...Russ wasn't playing when he said the order came from higher ups. They were both on the line for that situation.

>But under all of that (And why I say borderline jealousy), I
>think Russell in the film (not sure if in real life) wanted to
>be assured that Frank loved him more than he loved Jimmy.

Yeah the jealousy was there. When he saw Peggy happily dancing with Hoffa when he'd been trying to connect with her for YEARS that was clear as well.