Ann: Singapore Court of Appeal Dismisses Bayan's Appeal, page-6

Of what relevance is the question whether BCBCS had the ability to fund KSC themselves? I can only speculate that Bayan claim BCBCS could have mitigated the damage by fully funding KSC by themselves.
Regardless of the question whether BCBCS was obliged to do so, from my understanding the central issue was less funding but the lack of coal supplies by Bayan which the court ruling actually found to constitute a breach of the JV deed. So even in the hypothetical case of KSC being fully funded I doubt that there was a suitable alternative coal supplier in the middle of the jungle who would have allowed to sustain production.