Malaya's rubber and tin mattered to Britain's war finances

Would keeping Malaya's rubber and tin materially help Britain in the war?

Yes. The commodities supported war production, export earnings, and the financial position of sterling.

Keeping Malaya would preserve the rubber and tin earnings that helped Britain's wartime finances. Those commodities also supported the war effort directly. Losing them increased financial pressure and made it harder to sustain sterling. Retaining Malaya would therefore bring financial benefits alongside the military ones.