I think there are a few things:

1. Yes, nitrates (nitrosamines) are proven to be carcinogenic
2. Yes, cured meat is a source of nitrate
3. Yes, eating fewer nitrate-containing meats may reduce your cancer risk

However, we don’t know what the exact process for curing the alternative meat is:

1. They may still use nitrates, just not synthetic ones:

Here’s something worth understanding: most commercial “nitrate-free” or “uncured” bacon and deli meats aren’t truly free of nitrates. They use celery powder, which contains around 50,000 ppm of naturally occurring nitrates. Spinach powder runs about 30,000 ppm. When added to a meat mixture at roughly 0.3% per kilogram, celery powder delivers 45 to 60 ppm of nitrates, enough to function as a curing agent. ^1

2. They may smoke the meat. Smoke (soot) is made of polycyclic aromatic hydrocarbons (PAHs or PACs), another well-established carcinogen^2
3. They may use other, unspecified and unsafe methods

So in basis, this argument is sound. Whether it’s also a talking point that’s abused by the cured meat industry to sow doubt is another thing - most likely yes though. The playbook is probably just handed down to them by big tobacco and big oil.

E: a few things because Lemmy apparently doesn’t handle MD footnotes well and I didn’t finish a sentence I started.