Iiuc:I'm not 100% sure if intent is required, I think not, but either way, it is a judgement call, and the ump can use their judgement to decide whether the fielder was interfered with. The fact that it was a infield fly means that nothing the runner did, even if he wanted to rugby tackle the fielder, would have cost the fielder. The ump had every right to not make the call even if it technically was interference.
Here is what I found, and it sounds like a no-brainer.https://baseballrulesacademy.com/official-rule/mlb/infield-fly/If interference is called during an Infield Fly, the ball remains alive until it is determined whether the ball is fair or foul. If fair, both the runner who interfered with the fielder and the batter are out.
I wonder why that is. What loophole are they trying to prevent for?
