User blog comment:Miskos3/Fairy Tail Episode 241: Tartaros arc: Devil Reincarnation, Review/@comment-4933386-20150711153839/@comment-25111584-20150711174816

Then Virgo just has to revert to her gorilla form and dig the hole.

And the characters spent quite some time talking about it. Too much time for Lucy to not think about it. And, no, Lucy did not use Virgo. ._.

The obvious reason is that Mashima just didn't think about that method and wanted to show off Erza's new armour. /o/

The FTverse reason is what Misk stated. /o/