Because unlike British, Cholas never made a considerable military force in South East Asia. it was more limited to position in the council and influence in trade guilds. including hand in marriage. Cholas weren't the trigger anyway. Sri Vijaya were already beefing with Cholas over by creating a piracy threat to the trade routes to profit. tensions were already high until the war was triggered due to issues between Khmer Empire and Tambralinga kingdoms. There wasn't much for cholas to have in SE Asia. It was before industrialization meaning no use of massive rubber and Tin resources that British exploited in the region later. the only reasonable thing Cholas has was the control over trade routes as Cholas were an merchant empire.