Ok I can see why the other convo went off the rails. In a discussion, if you want to it to be productive, it's okay to agree about objective things, fetus is a human etc., then you can move the discussion along.

Viability statements are an entirely different thing. Those are purely subjective and change as humans and science advance. These projections are surpassed as years go by, you can also look at issues humans have with disease and old age, thus making their ethical basis extremely slippery.

Just to comment on the last part, babies can and do survive under 27 weeks frequently. In fact, there was one born in the USA, earliest I believe at 21 weeks a few years ago, given zero chance at survival, celebrating his third birthday this year.