Is it permissible for someone who intermittently experiences the emission of gas to be treated as one with perpetual incontinence on days when the event is continuous, so that he performs ablution upon the entry of the prayer time and disregards what is emitted thereafter? And can the obsessive thought of gas emission transform into a physical reality due to fear?

These are merely whisperings (waswas), and their cure is to turn away from them and ignore them. It is not prescribed to perform ablution (wudu') merely due to a doubt about something having exited. Whenever you doubt the invalidation of your ablution, adhere to the original state, which is purity. If it were assumed that wind exits from you continuously, then you would have the ruling of a person with chronic incontinence (sahib al-salas), but most likely, it is nothing but waswas. As for the transformation of imagination into reality through fear, its explanation belongs to specialists.