Wow. First off, any food that contains fiber can cause gas. The more your gut bacteria is used to being fed fiber, the better it is at handling it. So, suddenly increasing fiber is not a good idea...bloating and gas will result.
Second, the bigger sources of purine are alcohol (yeast and fermented yeast) and red meat. Cauliflower is pretty far down the list as gout trigger.
Lastly, you can develop an allergy to any food. There are some more common allergy triggers, such as shellfish. But, cauliflower isn’t any more of a risk than most other foods.
So, I rate that article as “true, but extremely misleading.” Someone just hates cauliflower. LOL.