We cannot allow ignorance or obscurity to be an excuse.
That is certainly true, but I don't think he necessarily did anything wrong as in your example. My take on this is that he never expected to get onto any level of DT and thus just kept his trust list as if it only mattered to him. I wouldn't see anything wrong in giving him a shot as long as he knows the significance of keeping a responsible trust list and doesn't have any other things against him that would rule him out as a DT1 candidate. I haven't seen anything thus far.
Just my opinion.