Why Argus kept single 4-inch guns

Why was HMS Argus not upgraded from six single 4-inch guns to six twins?

Space, firing arcs, and the amount of reconstruction made the upgrade poor value for Argus.

The proposed upgrade appears simple because it preserves the number of mounting positions. Argus, however, had little spare space and twin mounts would impose different weights and arcs. Fitting them in the same locations would require substantial alteration. The additional firepower probably did not justify that work on an old and constrained carrier.