i remember my teacher in pakistan reading us a shair that explained why mansoor didn't deviate from his claim of an-al haq... it went like this
an-al haq say ghaafil hoon to kyonkar hoon har ik sar-e-moo say aati hai sada tairi
in english... why should i forget/refrain from saying an-al haq the tip of every hair calls You out (You referring to God)
Rumi later on clarified what actually Mansoor was doing when he said anal Haq.. Actually Mansoor didn't belive in existance of anythign other than God the absolute monotheism wherenothign beyond god exists and that's why he claim I am truth because any other stand in his view compromised the ominpresence and all encompassing trait of god..
there is nothign beyond Him hence anal-haq ..
No wonder the litralist who had no sense beyond the litral meaning coulnd not comprehend these super-exalted notions..