Is it permissible to adopt the Shafi'i fatwa concerning doubt about seminal emission after a wet dream, or is that considered blameworthy seeking of dispensations, especially if the easier opinion is adopted in other matters?

There is no sin for the person afflicted with waswas (obsessive doubts) in adopting the easier opinion. Therefore, there is no sin in adopting the easier opinion regarding someone who wakes up and finds wetness and doubts whether it is mani (seminal fluid) or something else—namely, that he has a choice. This is a well-known opinion within the Shafi'i school of thought.