Yes. It doesn't make sense to dismiss Portuguese and Spanish as merely "European" languages for a German learner any more than it would to dismiss Spanish as a "U.S. Hispanic" language for an anglophone U.S. learner. The fact that they originated in Europe doesn't change the fact that they are also "non-European" languages.
There are more than a couple of reasons while the comparison between Germans learning Spanish and Americans learning Spanish is a poor one. (Much less a comparison with Brazilian Portuguese)
1. The distance. Most of the US is actually quite far away from Mexico. As you get closer to the border (Texas, California, Arizona, New Mexico) the rate at which non-hispanics speak Spanish rises considerably.
2. The economic and social relations between the US and Mexico are nothing like those between Spain and Germany. If I'm German, I can learn Spanish, move there, find work (okay, the example works better the other way around), and live with a minimum of hassle. It's another stable, developed country.
In contrast, parts of Mexico are almost literally war-zones (Juárez et. al.), and gaining a work visa, finding employment, etc is quite difficult, and even then it will be a dramatically different standard of living.
Linguistically, they are indeed European languages. Culturally, if you tell people in Argentina, the U.S., Macau and Nigeria that they are European because of a language they can speak, the label will lose all meaning.
They know they speak español, not mexicano, they know it came from Spain, and even a Mexican will brand you as a fool if you try to tell them otherwise.
Classification of language has nothing to do with ethnicity, background, where you were born or where it is being spoken.
Exactly. And if you talk to an American, or an Australian, or a Nigerian, they'll tell you they speak English and know it came from England. But no one, even in Europe, is learning English just to speak to the English.
if you tell people in Argentina, the U.S., Macau and Nigeria that they are European
What? Nobody was saying anything of the sort.
Brazil has a large population of ethnic Japanese. A number of them are able to speak Japanese. That doesn't make Japanese a Brazilian language. Nor does it make those born and raised in Brazil Japanese, aside from discussions of ethnicity.
Okay, let's back up a bit. My point in stating that some European languages are also "non-European" was that learning them gives a larger, partially-non-European audience and thus more motivation (economic, cultural, what have you). Even to an European, there is a difference between learning a language spoken by 45 million people on their continent and a language spoken by 350 million people worldwide. By the simple proximity/diversity theory, a whole lot more Swedes would be learning Polish right now - this is not happening to say the least.
How about Finnish/Norwegian? If the proximity theory holds no water, then I would expect that even though every Norwegian is within something like 200 miles of Sweden, you'd see almost no Norwegians speaking Swedish.
I'm not sure if these are the best of examples. Norwegian and Swedish are by and large mutually intelligible, probably on a level comparable to Australian and U.S. English. Norwegians essentially are speaking Swedish, without trying.
Finland has had a large (currently ~5%) Swedish-speaking minority for a long time. While a large amount (~50%) of Finnish-mother-tongue Finns can speak Swedish, this is expected given the Swedish minority, the previously large and prestigious role of Swedish in Finland, the relative populations (~5M vs ~9M for Sweden), and the relative linguistic isolation of Finnish.
I wouldn't claim the proximity theory holds no water - it's just not the entire story.
I believe the grandparent meant languages such as Japanese, Ethiopian, Thai, etc.