That is quite incorrect. Market makers are typically close to flat and are trading liquid instruments (assuming on exchange MMs like NYSE DMMs). The tail risk on a short duration trade of an exchange traded instrument is quite small, especially if the MM is not writing put options which this specific quote refers to. When writing a put option the premium collected by the writer is typically not enough to compensate for tail risk. Thus there is limited upside with extreme downside in the face of a tail event. Also the options tend of have longer durations (months or years). Firms pursuing this type of strategy are typically carrying a lot of mispriced risk on their books for a long time.