Why prefer the Pom-Pom for D-Day?

Why might the Pom-Pom have been slightly preferable to Bofors for D-Day?

Its rate of fire and ease of operation helped, and it was judged slightly easier to maintain than Bofors.

The preference for the Pom-Pom is specific to the D-Day setting. Its rate of fire and ease of operation support that judgment. A modest maintenance advantage over Bofors is another reason given for the choice.