Your assumption that technology may not be capable of helping us enormously down the road is much more of an assumption than the pro-technology argument. Because unlike the anti-growth malthusian argument, the reality so far for centuries has been that technology did indeed make life easier and better for people despite an ever growing population.
There's actual, consistent precedent contradicting all malthusian predictions across several centuries of human development, with entirely artificial political disasters mostly being responsible for any failures. On the other hand, we've not yet seen any concrete examples of human development failing in the face of hard natural limits to growth. Wherever it has failed has been because of mismanagement in some form or another, not lack of possible solutions.