The answer to your question is no.
The point that you cite is an issue of subsidiarity. A person that has enough has an obligation to give. A person that is starving has a right to that apple. Thus in that case it is not theft anymore but rather the starving taking something that is rightfully his.
I do not believe that this applies to the immigration debate as it is subject to a different set of moral principles.
This is totally incorrect. First of all, the owner of the apple is obligated to be sensitive to the needs of their fellow man. They are stewards of the gifts they have from God and in their stewardship they are called to invoke their conscience which MAY instruct them to give. This is a matter for the apple owner and God.
Secondly, the person who is starving has no “right” to something that is in the stewardship of another. While their taking of the apple may be mitigated regarding the seriousness of the sin, they do not have carte blanche personal authority to determine it is their “right” to take the apple. They first have an obligation to explore other alternatives to taking the apple without permission (ie asking for it and are required to respect the answer they recieve). In the absence of being able to get permission, they have an obligation to “repay” the apple owner.
In short, a starving person has no right to demand that another satisfy their hunger.
I think that the point Mosher is trying to make is related to the following from the Catechism:
2408 The seventh commandment forbids theft, that is, usurping another’s property against the reasonable will of the owner. There is no theft if consent can be presumed or if refusal is contrary to reason and the universal destination of goods. This is the case in obvious and urgent necessity when the only way to provide for immediate, essential needs (food, shelter, clothing . . .) is to put at one’s disposal and use the property of others.
In this case, one may make use of another’s property in obvious and urgent necessity but they are then obligated to compensate them as soon as practical. Also from the Catechism:
2412 In virtue of commutative justice, reparation for injustice committed requires the restitution of stolen goods to their owner:
Jesus blesses Zacchaeus for his pledge: "If I have defrauded anyone of anything, I restore it fourfold."193 Those who, directly or indirectly, have taken possession of the goods of another, are obliged to make restitution of them, or to return the equivalent in kind or in money, if the goods have disappeared, as well as the profit or advantages their owner would have legitimately obtained from them. Likewise, all who in some manner have taken part in a theft or who have knowingly benefited from it—for example, those who ordered it, assisted in it, or received the stolen goods—are obliged to make restitution in proportion to their responsibility and to their share of what was stolen.