there's no reason he should be.
Bear in mind that these historic mining operations were developed for purely commercial reasons, on behalf of people who in quite a few cases never saw them; he is just carrying on the tradition, in that sense.
I'm also not very comfortable with the whole idea of exploration of marginally breathable workings. One of my contemporaries at CSM was suffocated in Wheal Jane in the 70s; when I was working on the London Water Ring Main project in the 80s, there was a double suffocation involving a young engineer who went inside a sealed welded pipe at the bottom of a shaft out of curiosity, apparently not realising that it was sealed because it contained an inert atmosphere, and of course his 16-year-old chainman went in as well.
I was in Aberdeen about 3 years ago when a triple suffocation occurred on a vessel tied up about 3 berths along, in this case involving Polish seamen accessing a former chain locker with a single access and no ventilation, who had left their BA outside because of the small size of the hatch. Again, one went in when his mate didn't reappear, etc.
these things aren't remotely amusing, either at the time or subsequently.
I wouldn't go into places like that. I was interested a while ago in a trip into some old ironstone workings in Northants, but dropped it when people started talking about poor breathability. I do at times, get the impression that this forum contains a fair few people who don't understand the nature and probability of the risks they are taking.
Actually cavers can be just as bad, although the practices of "squeezing" boulder chokes and the amateur use of explosives in digs appear to be much less common than they once were
''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.