Is it permissible to remember the greatness of Allah, feel remorse for sins, and contemplate returning to Allah, while inside the lavatory?

Remembering Allah in one's mind without moving the tongue is permissible and entails no sin. What is disliked, however, is remembering Allah verbally in such a state. So, if a person in the restroom sneezes or hears the call to prayer, they should praise Allah and respond to the muezzin in their heart. Verbal remembrance of Allah in the restroom is disliked, but not remembrance by heart.