CE-608A pilot reported experiencing a rudder trim malfunction during flight. Flight crew continued to destination and after landing requested maintenance action.

Narrative

Aircraft X was in maintenance for RETRIM NOSE LEFT with autopilot on for the second time when we were assigned this aircraft. Early in the morning Aircraft X was released from maintenance for us to fly that day. We preflighted the aircraft and all appeared to be in order including the rudder trim was centered as well as aileron trim. When we took off the airplane was hand flown through 5000 ft in coordinated flight as well as neutral control inputs on the yoke at 200 knots and above. At FL210 we got a RETRIM NOSE LEFT CAS message. We followed the check list re-trimmed the rudder and reengaged the autopilot and continued the trip. When we were in the vicinity of the FAF we discontinued the auto pilot to check the trim status in anticipation of re-trimming for approach speeds. We found the aircraft flew in coordinated flight at 200 KTS clean with the left rudder trim still excessively trimmed left. We landed with no incident and on taxi back we noticed the rudder trim was so far left the display the indicator was yellow. I called maintenance to AOG the aircraft for repair. Person A answered the phone and I explained what happened and he said MEL the auto pilot since the incident happened with the autopilot on. I said sure I'll MEL the autopilot and I'm going to send a separate AOG for excessive left trim. Person A said what's excessive trim? I told him when you have to apply large amounts of rudder trim to maintain coordinated flight. He said Textron (I think that was the vendor he stated) told him there is no such thing as excessive trim and you can fly the plane all the way to the stop of left trim. I said I don't feel comfortable doing that. He said I don't understand what excessive trim is. I asked Person A if we can patch in a call with the Person C since I was uncomfortable with the dialog to this point. Person A said I don't want to talk to Person C and preceded to question me what was excessive trim and at that point wasn't accepting of me writing an AOG. I told Person A I was going to make a few calls then. Call him back. When I called Person A back he stated he was sorry for calling me several times when he found out I was tending to the clients in our plane while waiting for the recovery. He also stated he didn't mean to appear to push me into a different direction it's just hard to fix these issues. I told Person A I understand it's challenging. I felt excessive pressure to MEL the aircraft instead of AOGing the plane for a problem that I didn't understand what exactly happened to the aircraft and this was the 3rd writeup for this problem and the rudder trim has changed from takeoff to landing without the autopilot engaged. Don't push crews into an area they aren't comfortable with.