There is nothing in Neil Young's biography or his own lyrics to provide any sensible explanation.
However, a number of reviews have compared the group, 'The Mountain Goats', and John Darnielle in particular, favourably with Neil Young. For example, amongst others:
His lyrics draw comparisons to Neil Young, although he would undoubtedly prefer Mary Chapin Carpenter (“I worship the ground she walks on.”) and the tracks sound like short stories more than toe-tapping anthems.
and:
The album then resumes the decompressed attitude from before, almost straying into Neil Young territory during Have to explode and in particular Old college try.
In the absence of any clarification from the script writers, it is possible that Neil Young's perceived pain was due to The Mountain Goats having usurped his position as the icon for angsty country rock.
The words spoken by the character could well be an oblique call-back to Don MacLean's American Pie where Bob Dylan was supposed to be "the jester" who stole the thorny crown off Elvis Presley "the king", although this may be stretching the metaphor a little.