I could be wrong but I interpreted the down votes as about incorrectly equating of Rust and C++ allocations. There are a few replies that address this better then I can (I'm limited here in that I grok Rust but not C++) but I believe the comment would have been more correct to draw similarities between C and Rust explicit allocation then C++ and Rust.
Hence why Linus is allowing Rust for certain Kernel aspects whereas he has previously rejected C++: https://www.theregister.com/2020/07/13/rust_code_in_linux_ke...