Perhaps. Compared to how the OPCW suggests that chemical weapons are normally incinerated and/or neutralized, airstrikes are by no means the preferred solution. But when you don't have physical access, and your main concern is preventing their use against civilian populations, they're one of your few tenable options. The number of missiles used might indicate that stockpiles were targeted multiple times to compensate for such possibilities. That said, the mission planners would likely--as a worst-case scenario--prefer to have the Syrians have to cordon off a contaminated base than risk the possibility of a future CW attack on civilians.