I think it is the hole, more than what’s going through the hole, that may have weakened it. But still, 140 years is pretty impressive.
We’ll never know, will we?
The tree was in a flooded area and sequoias apparently have fairly shallow roots. That’s being blamed as the primary reason for the tree toppling. It wasn’t healthy either, described as largely dead with only a few branches having foliage. It was going to fall soon, one way or the other.