What could reasonably be placed in Malaya (and Burma) to deter Japan from attacking British territory? Britain already had a significant numerical advantage in troops, plus over 250 aircraft. So, more troops or aircraft may not pull it off. Perhaps strong British forces in Burma, threatening the potential IJA northern flank? But how to get them there, and support them? And where do they get pulled from elsewhere in the world war?
Everyone potential opponent has a tipping point, where the forces amassed before them deter a planned attack. What's Japan's max level of risk they're willing to go to?