You can do both at the same time. If Impossible could actually succeed in making a meat alternative that tastes as good as meat, but is cheaper (e.g. because they don't have to waste a bunch of energy growing an entire animal), then they could be poised both make a ton of money (by being a major player in the global food market) AND help end factory farming/animal consumption (by providing a superior product).

Furthermore, this is such a research heavy endeavor, you need upfront capital to fund it, which means it would be hard to structure as a non profit. Structuring as a for profit is the right move, and it doesn't mean what they're working towards isn't a good cause, or that they are somehow ethically compromised.