Hi Colin

Interesting question. As I read the above, Declarer has asked for the lead to come from LHO, therefore, as you say, the AH is a major penalty card for RHO.

As LHO also has a major penalty card Law 50 D applies. This is from World Bridge - 

"Law 50D – Disposition of More than One Penalty Card In cases where both defenders have a penalty card, lead restrictions caused by partner take precedence over the obligation to play one’s own penalty card. Example 43: LHO on lead has the ♠J as a penalty card, while his partner has the ♠7 as a major penalty card. Declarer now prohibits a spade lead. This means that the ♠7 is put back into the hand, LHO cannot lead his penalty card and in the case where he retains the lead, he still cannot lead the ♠J Effective: January 2019 Updated: January 2019 Page 28 to the following trick(s). If declarer requires a spade lead, the ♠7 goes back into the hand and LHO has to play the ♠J. Although it sounds odd, it might be to declarer’s advantage to choose this option, so we still offer it. If declarer doesn’t exercise his options relating to the ♠7 being a penalty card, LHO must lead the ♠J, and RHO has to play the ♠7. The ramifications of each defender having a penalty card are not obvious even to experienced players, so it is incumbent upon the Director to explain them clearly."

It also seems to me that the fact partner holds the AH is now unauthorised information, and a lead of the 6H later in play may be suspect.

Cheers

Sharon