They'll be angry because their commission from the finance company will probably only pay out once you reach the 3 month mark or something. By settling/withdrawing immediately, he's probably had his commission payment rescinded.
I didn't even know you could do that on PCP, I always assumed there were heavy penalties for exiting early? Hence the standard rule of you can exit without penalty if you have paid of at least half of the contract value (apparently a note is still left on your credit file if you do this). Learn something new everyday
I think there are legally limits to how much can they punitively charge as an 'early exit fee' or similar if you want to pursue early settlement - usually the reason it's not done often is because a PCP will leave you in negative equity for quite a long time, so settlement fees at say 6 months in are usually well above the value of the car.
The 50% thing is related to voluntary termination, whereby you end the agreement and hand the car back - again, with PCP, you rarely reach the 50% mark until near the end anyway due to balloon payments. This is very different though - this is terminating the agreement and handing back, not settling early which is paying off the remaining balance in full (generally speaking).
That's obviously excepting these cases where it's taken out and paid early deliberately to access deposit contributions and is being paid off virtually immediately, before significant interest is getting accrued or paid.