There is a way around this, but I doubt HT would be open to it...
Leave AH1 online, charge $24.95 a month and don't support it, update it or change anything and remove AH1 forums from this message system. If people want AH1, they have to pay for it and not expect support for it. A disclaimer when they sign up would take care of that. Charge $14.95 a month for AH2 making the price, support etc. the incentive to switch to it.
Keep in mind just how old AH1 is. It's base program was written how many years ago? How much have systems progressed since then? I think HT is doing a service by supporting the low minimum system specs for AH2. He could have made them MUCH higher since about the slowest NEW name brand prebuilt system you can buy today is a 2+Ghz celeron.