It seems curious to count the monkey thing with the rest of it, but on the whole, it's a substantial indication of how lax CA were in handling him. They threatened to deal with him repeatedly, but never actually did.
Either you look the other way every time or take a stand on second chances. Mixing and matching doesn't solve the issue.
On the one hand, this is not the world's most problematic drinker. Not even the most poorly behaved professional cricketer. The public record counts only the one time where his drinking actually directly stopped him from playing a match and judging by the result of that game, he wasn't the only one who should have limited his intake. In comparison with the feats attributed to a selection of international players from the last century, even one who is now an Australian selector, Symonds has been quite a tame beast. It's entirely arguable that, but for the public opinion of it, he could have been managed.
If the internal feeling was that it was no big deal, it shouldn't have been treated like a big deal. In that case he should hardly have been punished, as idle punishments only entice clamour for stronger punishment. In other words, every slap on the wrist increased the pressure to be more punitive, rather than less so.
On the other hand, if any such indiscretion is considered too great for a modern cricketer, then surely the punishment should fit the crime. 3 years ago, it proved acceptable to attempt to fight rugby players, why is attempting to watch them more serious? How many times can you threaten to tear up a contract before it's no longer the player's fault for taking his chances? That need not be rhetorical; the answer is one. If you renege on a promise just once, the floodgates open for you to be taken advantage of many times over.
If they had been tough, they probably would have had little choice but to sack him early in 2006. It would have appeared utterly brutal at the time, but he would have had a chance to reboot his career, rather than driving it into the ground.