If someone who had no knowledge of handguns posted that they were going out to buy a loaded handgun so that they could practice circus tricks with it, would you not as a responsible human feel some need to do or say something. If the person then killed themselves or someone else while practicing said circus stunt would you not feel some form of guilt if you didn't......... I think this post went beyond a trigger in a too small tank.
Do we know if this person is a minor? If so, hopefully, the lfs wouldn't sell to him but you never know.
Not to insult the OP in any way but two months in the hobby is still terribly new not only a time for learning but also very young for the tank itself. Especially for an exotic species such as an octo. People I have known have done months, even years of research and preparation galore to house an octo and then only had mixed results. We, as a group, discourage people from using damsels to cycle as it's cruel but won't speak out to someone who will very well kill such an interesting animal because of an impulse purchase.
Yes, there are many lines of thought out there. That's why you learn as much as you can from many sources and try to be somewhere in the middle. Can the poster get lucky? Sure! When I first got into the hobby years ago, I pushed and set up my tank, fish and all, in days, and in the end I had a catastrophic collapse. There is no rushing in this hobby and I can't help but feel bad for yet another octo (not at all unlike all the shark eggs) that will most likely die for lack of planning and resources.