I would worry more about non-linemen getting electrocuted. As noted, linemen(I was one long, long ago) know the hazards and take precautions. Many neighbours don't recognize the hazard. They are the ones who might assume a line is safe because the power is out. They may also see the open switch due to the blown fuse at the start of the feeder, and assume it is fine to move a downed conductor to drive by.
We get 2 to 4 lengthy outages per year where I live with most due to trees or large branches breaking a conductor. Our tap with 4 or 5 circuit miles and about 20 services averages one or two such outages per year. Although a small generator may not be able to energize such a system for long it could energize a small isolated section and a larger section long enough to kill someone if they happened to be moving a conductor off the road.
I have personal knowledge of one of our contractors being electrocuted with back-feed from a small generator while working on a de-energized line. It was in 1968 at Crossfield, Alberta. The crew was reconfiguring some lines and supplied a small generator to feed the Esso gas station (no longer there) at the highway. They followed proper grounding procedures and finished their work. The lineman was electrocuted when he removed the ground with the generator was still running. One would have thought that impossible because the generator would fail if feeding a grounded system. However, this was a generator purchased from the old DEW(distant early warning) line system. It was designed for greater reliability with a feature that collapsed the field(so it could not generate but would still run) in the event of a fault.
We can't anticipate all the things that can go wrong and must be very careful to ensure there is no possibility of back-feeding to the utility power system.