Not because of altruism, is the conclusion. Altruism is not favoured by evolution; it is at the expense of the self; can be detrimental to self interest and therefore is not selected.

A) I see no reason to assume that altruistic actions cannot be instinctive, so saying that something is instinctive is not, to me, a defeater of the notion that it is altruistic.

2) Altruistic actions can be beneficial to the gene pool. If one's actions contribute to the survival of one's children or even of one's siblings or one's siblings' children they can contribute to the survival of one's genome.