Interesting analysis! I think there are a few important effects that aren't being considered.
1. When the block reward is halved, inflation is halved as well. Is this halving already priced in by the market or will it result in an upward pressure on the price?
2. It was acknowledged that the referenced analysis did not take into account the result of a double-spend attack on the bitcoin price. However, the effect of a detectable double-spend attack on the Bitcoin network is not isolated to Bitcoin markets. The price of altcoins often trend with the price of Bitcoin, so attacking Bitcoin may reduce the profitability of 'multipool' mining. Any alt-coin market vulnerable to the malicious hash-power would probably go into panic mode.
-Alex Leishman