Apparently, the source is in Norman Lamm’s book. I found a blog discussing an audio clip on YU’s website called “Concise Methodological Manifesto ” or rabbi Jeremy Wieder of YU. He addresses that quote in this audio. If he says it exists, then it exists. From the blog:
[Someone asks <Rabbi Jeremy Wieder>, “there’s actually a deah that Rabbi Lamm brings in his book Torah U-Madda that you would make a bracha on machshirim.”]
You know, I happen to have a nice relationship with Dr. Lamm, and I won’t want to do what one of my no-longer-present colleagues did who got up, and, you know, made fun of the book and something like that, I think it was one of the things he picked on–I don’t know what deah that is, I think its a silly deah [student tries to interject] I understand that, I understand that. I think that part of the problem that disturbs me about that point of view is that it makes the assumption that if it weren’t talmud Torah then maybe we shouldn’t be doing it. That may not be what the deah says, but I don’t think you make a bracha on your calculus or your physics–even though I think they are magnificent subjects, I don’t mean to exclude history either, it’s of a different nature–I’m belying my science and math roots here–I like things that tend more towards absolute truth then not, postmodernists aside, but the fact is that I think they’re incredibly valuable, I think the study of–particularly the natural sciences–for many people, maybe the humanities for others–can be incredibly religiously inspiring, spiritually inspiring, morally furthering and they’re wonderful enterprises. They’re just not talmud Torah. For me, personally, what I’ve chosen as my life’s enterprise is talmud Torah. But I think that there are many different darkhei ha-chayim, and even for the person whose primary occupation is talmud Torah there are other valuable subjects to study, but you don’t have to call them talmud Torah for them to be valuable.