Going back to Justin offering Rob the job - it does seem implausible. Bound to cause ill feeling with Adam, you'd have thought he'd at least have a word with Charlie...
Also, he initially employed Lilian as his social secretary, because she knew the socual ins and outs of Ambridge and its environs, and he wanted to get in with the locals and who to cultivate, but now he's completely ignoring what she's saying. I can see in other circumstances... "AIBU to offer the job to this man who everyone is turning their back on, because his wife is on trial for stabbing him, and they're all her cousins. Plus he was bullied or something by my previous manager, and I think someone needs to give him a break and I have a vacancy." If that's all I knew of the story, I probably would be thinking, yes, someone should give him a chance - though for a job he's actually qualified for/has experience in (mind you, Rob probably told Justin in the phone chat that he'd been running Bridge Farm single-handedly, before Helen's [little chuckle] became too unmanageable [stifled sob], it's been so hard....)
But even so, why isn't Justin doing just a little more due diligence and background checking into what went on before? He surely can't have got to this age and been running companies like Damara if he's always just taken the word of anyone who sounds charming and plausible without doing any reference-checking or whatever, because in that case, he wouldn't have made millions, he'd have lost them.