Coinlim,if you make a trade at a decentralized exchange, the exchange itself never touches your assets. Accordingly, even if a hacker would somehow be able to hack the exchange (in spite of the above), the hacker can not access your assets. If you make a trade at a centralized exchange, however, you normally hold assets at that exchange until you withdraw them to your private wallet. A centralized exchange can therefore be hacked and your funds held at such exchange can be stolen.
As this exchange is a DEX, we feel that it is appropriate to award it a security score of A+