So while Ackman deserves critisicm for oversizing his VRX position, people take that way too far. It wasn't that wrong mathematically, its more that it was too high compared to what most people can tolerate in terms of drawdowns especially (and here was the problem) that a concentrated portfolio has multiple bets at the same time. His VRX problem turned into issues in other stocks as some of the funds who mimic him started to liquidate and shorts pilled in. So the bet 'poisoned' other bets. However, that is mean reverting over the long-term (Burger King/Mondelez and other companies couldn't care less about VRX's trouble's).
So if he oversized VRX, it wasn't by all that much (I'm assuming the goal is to maximize wealth growth over the long-term). The problem was that he was wrong (about the % chance to win by underestimating business risk). But to take that mistake outside of the context of all the right decisions he has made over the years (when he got the % chance right), its just to want to be wrong about him going forward
And with regards to Gotham Partners, there you have a similar situation, its not that the investments were bad or that he sized them wrong. Its that there was a mismatch between his goal to maximize wealth compounding (effectively his max tolerable drawdown) and of his investors. That does not mean that his picks didn't had positive expectation (in excess of the what the S&P500 returns) or that he is gambler. Its that he has a far higher tolerance for risk while betting in a overall context of positive expectation. Most of his observers and critics also dont have that kind of risk tolerance, so their tendency is to be uncomfortable when they see him behaving that way.