re: Neurologist said he is considering filing with a judge to remove my FIL from his finances

Have him interdicted if his finances are such that someone may be able to take advantage of him and cause great harm. A POA doesn't take away his ability to f things up, it only grants equal authority to someone else. By interdicting him, which is basically what the doctor is suggesting, you take away his capacity to make decisions about his own care, finances, etc.

BTW what the doctor is probably talking about is a PEC, physician's emergency certificate, which is different from a CEC (Coroner's Emergency Certificate). A physician can "commit" him, which is a psychiatric hold, for 72 hours, if the coroner concurs, it moves to 14 days. So the doctor can actually do something on his own authority although that authority is limited. It sounds like the doctor has your FIL's best interest in mind, you should get your wife to work with him and an attorney to get that interdiction done.