As a professional Electrician(not Lineman) and Solar Installer/enthusiast, I also dont understand what is wrong with his statement, and would like to hear your education. What is dangerous?This statement of ignorance is so wrong on so many levels and is putrid because it's so far from the truth.
Obvious you have no training in the electrical field. So for anyone reading knows the truth this a dangerous statement.
Any inverter that connects to the grid must meet UL listings, as specified by the NEC. This means that the inverter will not backfeed the grid when it is not supposed to be doing so, i.e. be safe for Linemen. Also as Quattro said, any Lineman should know how to work safely, like me as an Electrician, if solar inverters are a danger to Lineman, then it is a basic safety training issue, not an added danger from solar equipment issue.
If a solar inverter were to malfunction and accidentally backfeed the grid while the grid is down, the most likely scenario is that the the grid down area would be large enough that it would basically be a dead short to the inverter, and either trip the inverter out, or fry it, in a very short amount of time, like seconds.
Again, I just dont understand your beef with his statement.