That's very true. I think that's part of why he got into Harvard and why Maryland gave him their top scholarship - both schools noted his dual interests in personal communications with him.
I think that's also why Hopkins has been a little disappointing - the classics people loved him, and wanted him to go all-classics, the engineering folks liked him, too, but were a little nonplussed by the classics stuff.
The funny thing is, I can see how each interest is really just part of the continuum of the same person, the single personality.
sitetest
The advice that in the end people initially pursuing diverse double majors generally end up having to choose one is generally sound. Indeed, when the interests are this diverse, it is a case of pursuing a double degree, as a B.S. is not a B.A. for a very good reason. As you point out, the advice may not apply in this specific case, but in my experience of advising incoming students, even in most potentially exceptional cases, the general norm rather than the exception prevails, and one can usually not be sure of the exception prevailing until after the fact.
If he is really intent on pursuing both, I would suggest Maryland. While generally one gets a better education by being challenged by the best peers one can find, so being in the top ranks of a school is detrimental, in this case I would think that it would be useful as the dual interests will prove challenging enough (this is spinning your post 56 in a direction which you anticipated but did not do). If, however, the Harvard Classics department is able to provide recent examples of students who have successfully pursued similar doubles there, this would reduce (though not eliminate) the relevance of the point.
That said, it has been said (I do not know how accurately) that the hardest thing about Harvard is getting in, which might eliminate the point.
Classics is also a good pre-seminary degree and if done well—integrating most, if not all, of languages, philosophy, literature, history, and patristic theology (there are a few programs that do include the last) —a very good degree for people who will be dealing with people. I am guessing that your son’s competence is in the linguistic end of things—today very good Latin or a level of Greek that exists is one of the goals of such a program, while a century ago, it was an admissions requirement.
I would also echo Mad Dawg’s concern on the quality of chaplaincy etc, and suggest that this, while generally relevant, ties particularlly into classics considerations, if the program is well-integrated. A few 20th century popes made the point that one’s education in Catholicism needs to be porportioned to one’s educational level, and that one major problem in society is that this is not happening, which applies across the board. In areas that are most pertinent to the faith, such as philosophy, it is doubly true. If the classics department does include a serious philosophical component, he should have ready access to a Catholic mentor who is competent in these areas. There is an Opus Dei presence around Harvard (or at least there was two decades ago and I doubt very much that it has gone away) which will include at least one, and probably multiple, people capable of aiding in this area—like every religious movement in the Church, Opus Dei has strengths and weaknesses, and philosophy is one of their strengths. The classics-engineering double actually sounds like classic Opus Dei (particularly the engineering).
Like Mad Dawg, I greatly respect the eastern province of the OPs, but given all that you have said about Hopkins, I doubt that would off-set the rest.
I have no idea about Maryland in the chaplaincy area, but this is worth considering and talking through. Especially if Maryland’s chaplaincy is awful and he opts to go there, the talking through can be profitable. I went to a school with a pretty bad chaplaincy, and for the handful of us that worked to change things, the experience was undoubtedly good (I went onto seminary and now teach theology) but a great many (most) fell away completely or became/remained cultural Catholics with cultural habits and virtually no belief.
I hope that is helpful.