This is probably because quoting the translated law looked like attempting to intentionally obfuscate.
The very point is that IPR can be defended by using some other name for it than "patent", so quoting a piece of law that says what cannot be "patented" is not relevant when the rights are granted by some other law - and in the case of Argentina they should be, because it is signatory to international convention that obligates it to have such a law.
Seed rights don't have to be protected by "patents". For instance, in my country, the name (translated to English) "plant breeder's right". It has its own piece of legislation, and it is in many ways like a patent, but it is not called a patent. In the US, the same thing is called a patent, but that is just terminology.
For example, according to https://en.wikipedia.org/wiki/Software_patent most countries exclude software patents or computer programs, and lots of them are also signatories of many of the same treaties. So, its a very complex situation.
Also, and curiously, it seems that the article 1350 of the Civil Code Of The Russian Federation, is almost the same word by word. So, my guess is that this kind of wording exists in many other countries.
http://civil-code.narod.ru/ch69-art1349-1350.html
PS: I find it amusing to be down-voted just for translating the text of the law. I swear didn't write it, lol.