If such a question would be posed to me, I would stress that highlights rendition on film is way better than with digital, and I would advice him to look back at the most contrasted of his digital pictures taken in those last years to check the highlight clipping. The "shoulder" on the highlight is the main reason why I would not consider switching to digital for quality work.
He would certainly enquiry about the resolution of film against good professional digital cameras. I'd just say that I also have, and use, a digital camera. For certain kind of slow and careful work, film works much better for me. I would not quantify the "resolution" of my slides when scanned at 4000 ppi, but it is way above my 10 mp serious digital camera. I would rate it somewhere between 15 mp and 20 mp. And it's more than enough for my purposes.
He would certainly comment on how expensive film must be, giving me the occasion to point out that with film all the activity is more reasoned, more studied, resulting in more roast and less smoke, and that I develop film by myself. So let's say 50 135/36 rolls a year at 3.6 Euro per roll + 1 Euro per roll for development cost me around 200 Euros per year. That's not so expensive. I am still using material of the Eighties, investment in glass and cameras has a very, very long use.
I would also stress that I actually occasionally sell pictures, and film comparatively sells much better than digital in my case, so that I have much accrued the percentage of film work.
At this point I would briefly tell him about how rewarding I find to develop slides by myself, how magic and fulfilling is the entire process, makes me feel good in Witchcraft.
As he certainly would be quite tempted by the analogue side of photography, I would finally recommend following APUG and looking on eBay for some second-hand film SLR.
Here in Italy there is still no problem in finding film, you can easily find it at your photo-optician round the corner, that's probably why no digital fan ever comes to ask me such questions. It's usually film fan who come to me to express how they agree with me, instead.
Fabrizio
PS Be evangelist not confrontational is my advice. Spread the gospel.