A humans life is not worth more than anything else on the planet, no more, no less
So it’s an equal trade, a pig life for an equally valued human life. One of them is going to die regardless.
And from certain points of view, since that pig would not have been born if it weren’t for this, that is one more life created in this process. It may have been a short life, it may not have been the highest quality, but if we’re valuing all lives equally and believe that life is a good thing, the fact that that pig existed at all, regardless of the circumstances of its birth, life, and death, is something to be happy about.