I think they may have been referring to not an "available engine" but more of "available engine technology". As in, it's unwise to attempt to develop an engine far beyond one's own capabilities in tandem with a platform that is reliant on this extremely difficult task.
Some insight on Indian RnD effort toward engine and overall challenges facing them, there is however a part i disagree
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Regardless one have previous experience or not, it's actually quite normal process for an engine to be developed concurently with the platofrm, say Su-27 was developed together with AL-31F and in US F-100 was developed with F-15's. F-135 and 136 developed for JSF/JAST program and of course EJ-200 developed for Eurofighter program.