I think that is not correct. I think they mean there is no optimization at the ASM level, so the inline code is not optimized, which is correct operation.

I just did a test, comparing a binary compiled directly, to one compiled with SRC.
The resulting binary was the same in size and content.

I used OT(9), and I can assure you without optimizations the file is much bigger.

I then added some inline assembly. The file contents changed, but the size stayed the same. I attribute the size staying the same due to some packing.

I added a few more opcode, a mov, some incs, and the file size increased slightly, but not the huge increase I would get if optimizations were off.