I'd Try
Humboldt:
IAW the Memo:
1. See if MPC will amend your order. Cite the memo as the reason.
2. If they won't, get them (or someone at your base) to draft the supporting letter mentioned in the Memo, and have it placed in your personnel records. I'd try to get it recorded locally as well as MPC. If you are still technically a Reservist, I'd get it recorded at ARPC as well. Again: if they resist, cite the Memo.
3. Call the POC at the bottom of the Memo for more info. Probably not the same guy, but I'd guess it's the same phone number.
4. As a last resort, the Memo by itself should support in most cases (since it says you are 12301(d). But more support is better).