Our employees are in training for the first 6 months lol so 3.5 months would still be classed as a learning curve at that point & they would be given extra help etc which sounds like what they might be doing by having him listen in to another employee. (Men don't take kindly to being told they aren't doing the best job though & if he is quite stubborn he could be taking this 'help' as an issue against him which it might not be.
Having said that our employees are in probation for 6 month period and we can ask them to leave without needing to give any reason within this time, but this rarely happens unless there has been some serious misconduct as the cost of recruiting and training is high so we would prefer to give extra help where needed.
I don't really know much about american employment law though & don't know if it's the same regarding the probation. After the probation period has ended then we have to follow the correct disciplinary procedure that is set out in their contract.
I would say that at 3.5 months that they aren't trying to underhandedly get rid of him as I think they may be able to without reason at that point (you would have to check the law on this though) and that maybe he is just getting confused with the different procedures & being stubborn like you say he can be ( maybe not listening too well - ALL men have this problem haha)
If they are giving him the extra help such as listening to the other advisors I would say they are trying to ensure that he does get to grips with the job, as after all they have invested money into his recruitment and training.
Id really try and have a calm chat with him if you can, explain your concerns & ask him to be more specific about the problems. He may just be sounding off as he's not keen on the job & doesn't realise how worried it's making you.
However if you feel that he is being targeted then try & get him to arrange a meeting with a witness where everything that he is unsure about can be documented & he'll then have proof if they change the goalposts.
It does sound though like he is just maybe taking time to adjust to the job & is looking at their help / advice as they are picking on him (lots of men do this) the amount of male employees that take offence when you have to give negative feedback compared to female is incredible. The women just take what you say on board & try & do better while the men feel like they are being picked on & try to come up with excuses... weird but that's what my experience has been.
Anyway, sorry for the reeeaaallly long reply, best of luck with everything, keep me posted how you get on
xx