I'd probably have tried something like this. Would have to be there to see the exact positions + know the table conditions etc, but seems like it should work. Even if the cue ball leaks out, leaving the purple ball against the end rail ensures no easy shot for the opponent.
If it feels like a double hit is gonna happen with the cb+purple, then that complicates things, might be avoidable with side though. Again, would have to be there on the table to feel out whether a double hit would happen or not. From the image, to me it looks like you can avoid it, if you hit it thin enough like in my drawing.
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My main issue with what Moritz did is that even if it gives a great safety some of the time, the % of sell-out is way too high. Not worth the risk at all. And this all leads me to wonder what he sees that I don't, because there's no way he would play that shot if there wasn't something that I don't see. Only other explanation I can think of is frustration/laziness, which I highly doubt for such a situation.