User blog comment:4Ferelden/A new interpretation of Starchild's motivation./@comment-1679409-20120703173310/@comment-4721065-20120704095318

That is a good theory, but if it was true, then the Catalyst would have no need to offer us its endings and would simply shut off the relay beam to prevent us from reaching the Citadel and making the choice (for a more complete list of things it could do that would guarantee Reapers' victory and eliminate the need to offer choice, click here.

I would say that the Catalyst harvesting the synthetic life alongside organics is a predictable outcome of his programming: eliminating advanced organic civilisations while letting sentient synthetics alive would certainly lead to those synthetics being "inspired" by his actions and wiping out all organic life, an outcome that is forbidden under his directives. To his insane mind, subjugating its brethren like that is probably an acceptable consequence of screwing over organics via Reapers.