Its just a difference of opinion. I am not being cynical here, it is similar to words like compassion, humanity etc. Different people worship different Gods. But a person of one religion, does not necessarily believe in other's religion. I agree with doing good according to one's situation, but altruism is a fancy word without further explanation.

Once it was said that earth is "flat", everyone believed in it. Until it was proven that it is "round".

The same cannot be applied to altruism, because how do you define, practise or prove it. Everyone has their own definition of it, varying in magnitude.

There are some questions like:

What is altruism?

How it can be practised in your life?

Has there been any proven studies done to validate its existence? If yes, than does it has consensus.

Why should one believe in something that has not been witnessed or is vague?

One cannot be forced to believe in something that is not practised / proven / have proper reasoning.

In addition i would add that in my original post, the condition was under "first sign of distress", survival would be more important than anything else.