The extended MSDU size is only available on 802.11ad devices, it doesn't affect any 2.4/5 GHz devices. Those are still limited to 2304 bytes.
And if you use a 802.11ad device (or more specifically a wil6210 device), the kernel will allow the higher MTU.
Furthermore neither A-MPDU nor A-MSDU allow you sending larger frames, these are just means of sending multiple frames in one transmission. This is already done by the kernel if supported by the hardware.
So the correct resolution would be "not a bug", not "won't fix".