This seems right. Even those non-consequentialists who argue for keeping the human race in existence usually do so based on moral reasons and principles that are comparable in importance to all sorts of mundane reasons and could easily be trumped. Here's John Leslie writing about such non-consequentialists:
Having thereby dismissed utilitarianism with suspicious ease, they find all manner of curious reasons for trying to produce benefits for posterity: benefits which anyone favouring mere maximization of benefits would supposedly be uninterested in producing! Some base their concern for future generations mainly on the need to respect the wishes of the dead. Others emphasize that love for one's grandchildren can be logically linked to a wish that they too should have the joy of having grandchildren.
(The End of the World, p. 184 of the paperback edition )
Many people on Less Wrong believe reducing existential risk is one of the most important causes. Most arguments to this effect point out the horrible consequences: everyone now living would die (or face something even worse). The situation becomes even worse if we also consider future generations. Such an argument, as spelt out in Nick Bostrom's latest paper on the topic, for instance, should strike many consequentialists as persuading. But of course, not everyone's a consequentialist, and on other approaches it's far from obvious that existential risk should come out on top. Might it be worth to spend some more time investigating arguments for existential risk reduction that don't presuppose consequentialism? Of course, "non-consequentialism" is a very diverse category, and I'd be surprised if there were a single argument that covered all its members.