Here's the question, though: how likely were other powers to engage in economic warfare with Japan if Japan were not engaged in active warfare with their friends and economic partners? Arguing that Japan was unable to become a great or regional power because they were reliant on foreign imports seems to be contraindicated by the fact that they were already one of the most powerful regional powers in the Far East and had been seen as such since 1905. Certainly, it was not a binary choice between either becoming an independently-great power and perfect subservience to the West. India, for instance, proved its ability to navigate the political shoals of the Cold War and retain regional relevance in spite of being reliant on foreign imports and expertise: even today, it still has a negative trade balance in over $100B in USD. Japan itself pre-war had proven its own ability to act in contravention to Western opinion by seizing Manchuria in the first place. The Mukden Incident saw no further response from the Western world than a League of Nations rebuke, to which Japan responded by withdrawing from the League entirely: no economic sanctions, no real punishments save for those Japan inflicted on itself. If the Marco Polo Bridge incident had somehow resulted in China caving again and demilitarizing or ceding all of Beijing and Tianjin (assume pure ASBattery here), it's unlikely that the West would have done more than write another round of sternly-worded letters. In spite of their economic interests in China, Western sentiment was not really hardened against Japan until the Chinese war had become a long-term mission of conquest and subjugation. You assert that Japan could have been smeared as a pariah, but until decolonization changes the entire game in the 1950s-1970s, I don't see any way in which this is particularly likely short of open war with China.
That said, it is an excellent illustration of the mentality the Japanese leadership had at the time, and thus serves as an invaluable insight into what Henry IX referred to as "requir[ing] Japan to not be Japan." There was indeed a sentiment within Japan at the time that it needed "its own India", by which we refer to a large combination of captive market and resource extraction colony. China was seen as the answer to this sentiment. Supercharge the Japanese economy by conquering China and denuding its own native industry or transferring it to Japanese ownership, forcing it to buy Japanese, and by extracting its resources to fuel the boom. It would essentially be Manchuria and Korea writ large. In this context, it may not be true that Japan cannot be seen as strong without having the option for perfect economic autarky, but it is accurate to say that certain elements in Japan, particularly in the Army, believed this to be the case.
