[sudosysgen]

Trading within a few seconds is not really considered HFT, it's mid-freq nowadays. High frequency is in microseconds end to end nowadays.

High-Flyer says it took directional bets and held positions, which makes at least part of it not HFT.

Also, I doubt that most quant money is in market making nowadays. That was true at some point and that's true of HFT, but I doubt it is of quant trading in general anymore.

Besides, High Flyer certainly isn't a market maker, or they wouldn't be a hedge fund. You can't really be both, hence with Citadel and Citadel Securities (Market Maker) are so strictly divided.