No, most likely not. Most likely, it is caused by faulty consumer electronics gear, which typically has poor filtering (If at all).
So, if the operator's station is compliant (Good chance it is if he's not having problems), then the fault lies with the neighbor's equipment, not with the ham operator.
Not likely. A lot of equipment cannot play well in a high power RF saturation field. I have been a ham for 42 years now and while I am "pro Ham" I am not a subscriber to "its your problem not mine" Either placate neighbor or restrict power out as it is not your "right" to interfere with their space.
The RF spectrum is not "their space"...
Such things can give also hams a bad name. I have never had a complaint where I live now but have in past many many years ago. When I had problems I restricted operation to times and power levels that would not cause problems and never tried to imply it was their problem. I supposed now they need to start making and labeling Ham Proof consumer electronics for people that have inconsiderate hams running 1.5kw+ next door to them causing RFI issues.
No, they need to just put filtering in place on their gear, to reject unwanted RF that can cause undesired operation.
If you lived next to an AM broadcast station, and you were getting RF interference in your home, would you expect the broadcast station to turn their power down?
No.
And neither would the FCC. The FCC will instruct the consumer to look at their device, at the Part 15 disclaimer.
Operating within your license restraints is not being an "inconsiderate neighbor". It's doing what is allowed per your license. Of course, I also add the contingent phrase,"If your station is clean, and within regs". And the regs also requires a RF field strength evaluation to be done if one is running high power.