I think you’re confusing terms. High Sync Speed is a function of a flash, not a camera. A camera has a max sync speed (usually around 1/200 – 1/250), which is the maximum shutter speed that allows flash. An external flash with HSS can get around this by using HSS to quickly pulse the flash and work above the max sync speed.
A flash without high speed sync can never go above the max sync speed of the camera. You can trick it into firing (not with the ST-E2), but you’ll get a dark band at the bottom, the size of the band depending on how far above sync speed.
True high-speed photography is shot entirely with flash and would never use HSS. HSS doesn’t freeze motion, a single shot of flash can. The speed of flash is so fast that it doesn’t matter how slow your shutter speed is. So in answer to your question, yes, flash without HSS can be used to make fast photography.
