Jude:
Even if the 4-ball is frozen to the rail, with the hemispere of the 4-ball extending just past the point of the side pocket, it shouldn't be too difficult to go straight into the 4-ball, with just a hint of angle (very, very minute) towards the inside of the side pocket, to have the cue roll-up against the wall of the side pocket. (Even if the cue ball bounces off that side wall slightly, I'm guess the result will still be that the horn of the side pocket will obscure a direct hit on the 4-ball, no?) I guess the answer depends on how deeply the pocket shelf extends into the pocket on that particular table, to answer the question of what kind of scratch risk this shot is...
A touch shot for sure, but as you stated, a higher percentage than going all out for an aggressive shot.
Pretty fun shot by Tony! I'll bet poor Trevor didn't think so...
-Sean