Appalling.
Threaten that you are seeking legal counsel to the highest level person you can speak with.
Some people who happen to also be teachers will always believe IEP mandates are B.S. and refuse to comply. It's disgusting.
And yes I would just elminate the pencil completely, no use in being "reasonable". You have nothing to justify to anyone and do not need compromise by having him write sometimes.
Best wishes, you have our disgust on this backing you up.