What is the strong legal evidence that permits a person afflicted by obsessive doubts (waswas) to adopt the easier opinion (al-aysar)? Is considering this a disregard for the waswas from Satan? And what is the view of contemporary scholars on this issue?

Taking advantage of dispensations when needed is permissible, and the whisperings of the 'waswas' (one afflicted by obsessive whisperings) are among the greatest necessities that call for him to avail himself of such dispensations. Sheikh Al-Uthaymeen holds the view that a layperson may choose the easier opinion if scholars differ, provided they are all trustworthy. This applies even more so to one afflicted by 'waswas'. For the 'waswas' to act upon the easiest of opinions is a form of ignoring the 'waswas'. If he is unable to ignore it, then he is guided to act upon an opinion that will relieve him from the burden of indulging in these whisperings.