I wonder what happened? HACE? HAPE?
They got caught in a snow storm and he suffered a heart attack. Very sad.
I've been through Gramphu on a bike, and the road they were on isn't *very* high, but it's also quite close to the start of their journey and if they hadn't acclimatised properly the altitude could well have been a factor (more likely to be HACE than HAPE). It's also very early in the season - the road to Leh is normally closed from September until June so there will probably still be a lot of snow around, and the weather will still be unpredictable. Not the ideal time to be there.
It's a pisser for his relatives who might be thousands of miles away, and for his colleagues on the tour who have to suspend their trip to deal with authorities in a place like Lahaul & Spiti...
Your trip is still the template of something I hope to do in a few years BTW. All the best Al.