Swift cannot implement ARC without conditional releases. Rust can. What Rust effectively does is compile an if statement into something a tiny bit more complicated (two if statements, really), in certain conditions. It doesn't need to. The if statement uses function-local information known statically, so it could be compiled in a different way without the drop flag. Basically, the condition already existed, Rust just inserts another one instead of piggybacking on the one inserted by the programmer. ARC needs new conditionals everywhere, and whether or not something will be cleared is often not obvious without looking at the whole program, and even then it could be undecidable.

I can't answer for Patrick, but I don't see the term "automatic memory management" as useful as distinction, I look at it more as a spectrum, and Rust/C++ fall squarely on the "more manual" end of that.