The only people who wish to be excused are those who do not really believe in God and the Last Day. Their hearts are full of doubt, and their doubts cause them to waver.
إِنَّما يَستَـٔذِنُكَ الَّذينَ لا يُؤمِنونَ بِاللَّهِ وَاليَومِ الـٔاخِرِ وَارتابَت قُلوبُهُم فَهُم فى رَيبِهِم يَتَرَدَّدونَ
innamaa yastaazinukal lazeena laa yu’minoona billaahi wal Yawmil Aakhiri wartaabat quloobuhum fahum fee raibihim yataraddadoon