Generally this argument holds very little water beyond making a gotcha-style bad-faith argument.

People understand that murder is illegal - but life isn't just two states. Alive or Dead. If we were living in 20,000 BCE then maybe we could be forgiven for thinking this way, but we live in an advanced, modern, (presumably) ethical civilization where life is about flourishing and giving everyone opportunities to thrive.

Focusing on the fetus's rights, yet condemning children to a life that's designed from the start to prevent flourishing is the conundrum people are referring to and pointing out the hypocrisy of.