﴿ وَلَا يُؤْذَنُ لَهُمْ فَيَعْتَذِرُونَ ﴾

“nor be allowed to proffer excuses!”

nor will they be given permission to offer excuses and so offer excuses fa-ya‘tadhirūna is a supplement to yu’dhanu ‘given permission’ but without being a direct result of it since it belongs within the confines of the general denial of permission in other words ‘there will be no permission hence no excuses’.