I don't know much of the trail details but I can't imagine that trees were hacked down to build it; to build a rough trail one just cuts back the underbrush and removes windfall obstacles, right?
The entire Indian Arm area on both sides and the islands from Belcarra to Indian River is already protected as a provincial park, isn't it (along with Mt. Seymour P.P. and the GVRD watersheds)? So why the need for a "witness" trail there to protect it from resource extraction (as in the Elaho example)?
Until reading about it on CT, I'd never heard of a trail going around Indian Arm. I don't think many know about it. So you're probably right, C wall, the number of people attempting the route would be small, and the trail would overgrow faster than people would maintain it. But all it takes is someone to publish its details in some Vancouver hiking guidebook (this may have been done already - I've no idea) and it may become the popular week-long trek version of the Buntzen hikes you mentioned. Something for Lower Mainlanders that can't afford all of the expenses of, say, a WCT trip.
About the Seymour Watershed part of it...a few years back I walked along the Coquitlam River trail upstream as far as Or Creek. On the way back (and I was now out of the prohibited area), a GVRD guy stopped me. He had gone to the trouble of fording the river from the guardhouse on Pipeline Rd. with his dog and running to catch up with me to give me hell for my trespass. How do you think the GVRD sits with the trail running through their out-of-bounds area? Do you think it's right that McPherson built the trail through it? Personally I think that hiking in the GVRD watersheds is nothing compared to the logging that has been done in them, but still I don't think McPherson had any right to build the trail there.
All human encroachment on wilderness areas has a detrimental effect on wildlife (be it minimal-impact hiking, hunting, logging, development, whatever) and I think sourdough has some valid concerns. Take the Grouse/Goat/Crown area, for example - that area once had large numbers of mountain goats, as did all of the southern mountains on the north shore. Now? None, because of relentless human presence. I for one have never let this concern stop me from hiking and it wouldn't stop me from hiking the Indian Arm trail; but my enthusiasm to explore the wilderness is tempered with some respect that my presence there is disruptive.
McPherson's apparent selfless efforts on this unimaginably immense project deserve Lower Mainlanders' thanks. But with today's topo maps and technologies, and proximity to Vancouver, you'd liken Mr. McPherson to Simon Fraser and Alexander Mackenzie? Give me a break! And Randy Stoltmann? Based on this project alone? I don't think so...