This institutional manipulation talk is bunk, page-40

Most retailers don't short and most advisors won't/can't recommend it (strict regulations) but you can still access shorting as a retailer (e.g. through CFDs). As for whether shorting is a strategy used to drive down prices, I'm not sure. I don't think any fund outside a hedge fund would do it but individual traders might do it for profit. I'd hesitate to say anybody would short a stock just to push down prices, it would have to be combined with a negative sentiment on the stock (too much risk, potential loss on shorts is unlimited).

As for the short numbers, looks like some shorting before the annual report but the number looks big because it's % of volume. If you look at gross shorts it was only 100k which is like $40k. Since it's such a small amount I wouldn't read too much into it - don't think it indicates anything special.