It was more an argument to be pro nuclear and not worry about lighting efficiencies in the first place.
I'll have to disagree here for a couple of reasons.
Even if you have an all-nuclear grid, you are generating much more nuclear waste per year (in terms of tons) from the extra power needed for incandescent lighting than the mildly-toxic materials you would have from LED disposal, and I don't think anyone would argue that the nuclear waste is safer than the LED waste. The toxicity from the LED materials only comes about if you break open the packaging and then either ingest or inhale the crystal particle dust, which is pretty much impossible when it's in a landfill. Once it's in a landfill, it's pretty much inert environmentally speaking.
Also it's actually not difficult to recycle LEDs. The substrate materials used are easily separable from the packaging. The problem is the logistics of separating out the LEDs from the rest of the bulb, and transporting them for recycling, and the fact that there is no universal standard at the moment. It's usually just cheaper to get more gallium and arsenic since both are waste byproducts of other industrial processes. That's also another reason why I don't follow your reasoning: since the main materials used in LEDs are byproducts of other industries, they are going to be generated regardless even if you completely stopped production of LEDs. It wouldn't matter if the grid was all nuclear or not.
I won't even get into the huge impracticalities from switching to 100% nuclear, which another argument entirely.
Source: I'm an electrical engineer that has worked with a lot of semiconductor fabrication processes and materials.