Indomitable's presence would probably not cancel the invasion because Japan expected land-based aviation to support it. The likely defense routine places several Fulmars and Sea Hurricanes overhead, another group ready on deck, and replacements moving up from below as each layer launches. Radar warning would turn that arrangement into a continuous cycle rather than a single interception. Radio traffic from the coordination would also alert Singapore's fighters even if the historical message failure recurred. Attacked under those conditions, unescorted bombers would probably be forced onto the outer destroyer screen or broken up before reaching Indomitable and Repulse.
Chapter · 53:16-58:20
How Indomitable's fighter cycle could defeat the bomber attack
A standing combat air patrol, deck-alert fighters, and reinforcements from Singapore would meet the Japanese bombers in successive waves.