In geopolitical scenarios, things changes drastically, for ex. on one end you were ally of US on WoT, now the deeply strained relationship.
Srilanka's nearest neighbour is neither Pakistan nor China. All there access to most of the products are via India. Plus why would they form anti-India relationship with a regional power like India.
All Sr. AF can learn is counter-IAF strategies from Pakistan. But no matter what was the past, India will be their neighbor at the end of the day, which they have to live with it.
Any hostility towards India won't lead them to prosperity. China is making Srilanka as its distant base in hidden way but I seriously doubt that Srilankan policy makers will decide to indulge in tug-of-war between India and China.