Until it is a biggie! Taking chances is part of the job, but when it comes to power, I prefer to hedge my bets. That said, I've dumped the top of a pine that I misjudged by literally 6" and damn near tore out a service drop to a house...bent the mast and loosened the waterproofing coming into the cabin. Luckily the HO was building a new house so it didn't much matter, but it is certainly something I wouldn't want to make a habit outta.
A slap on the primary is always a biggie. Ive done it, not on purpose, but I can tell you a silly little story about a slap on the primary and me in the hospital years ago. There is NO reason to touch your work to a primary line. especially to the point the line is slapping and rocking the poles.
I prefer a little more clearance myself....and I found the undercut on that poplar a little deep for my taste...well past half way. Decent hinge and all that, and they did have two ropes, but seems a little deep for my taste. I likely would not have rigged that big dead tree out without a crane, there was plenty of room and it would likely have saved$ on the job. I've worked on poplar plenty. The thing I didn't like about the rigging was that it seemed as though they either didn't account or care for the reality that the limbs were going to break up after being cut once the load was applied to the rigging. If you watch closely, there are many smaller, broken pieces contacting the house (which didn't exactly look like an inexpensive build).
My .02, I wouldn't hire those guys.