Not only is it never allowed to be silly, it's never allowed to be glorious, to be powerful, to be beautiful.
Circe does not have a magnificent palace filled with nymphs and golden furniture. Calypso does not weave on a golden loom, her cave full of mighty trees dripping with grape vines. There is no Nausicaa and Arete in their palace of Orichalcum and magic boats which pilot themselves. Penelope does not have a wedding bed carved from a mighty olive tree, rooted to the rock of Ithaca.
Because Nolans movie is about the collapse of a cultural empire because people didn't respect God's laws enough. It's about a civilization degrading and fading, so he has no use for any of the majesty and wonder and humor of the homeric text. Everything needs to be grimy and decaying, collapsing in on itself.
And Adaptations are allowed to be different and it's broadly a good thing to have a strong directorial vision.
But it does remind me of Nolans Batman, which had no time for boy wonders and found family and silly puzzles because it needed to be about the righteous necessity of the post 9/11 surveillance state.