Unknown. My guess is that if the A01 is the second in the chain and set to DP 1.2 Disabled, it should not be an issue.
His specific question was if the primary in the chain is A03 DP 1.2 Enabled, can you then use an older revision as the secondary DP 1.2 Disabled. That link does not really discuss this specific question.
Just a quick update. Been using the setup Chris described above and it seems to be working fine.
The only issue I've had so far is similar to this post where the monitor gets disconnected when being powered off (although in my case the resolution seems to be fine and it powers back on properly every time). It is just annoying because it moves all the windows from my secondary monitor onto my primary monitor.