While the numbers provided by the sources seem to be strictly correct, they are lacking a significant amount of context. Once this context is injected into the discussion, the manufacture of Wind Turbines does not create as much radiation as Nuclear waste.
The primary claim, from the Institute for Energy Research (second quoted block in the question) seems to be true. The 4.9 million pounds of waste number is calculated using data from an MIT Research study and an Institute for the Analysis of Global Security study (although the IAGS study quotes a Chinese Society of Rare Earths article that I cannot seem to find an original source for.)
The radioactive waste from Nuclear power production seems to be quoted from a Nuclear Energy Institute page that claims that
The nuclear industry generates a total of about 2,000 - 2,300 metric tons of used fuel per year.
which would translate into roughly the numbers given by the report.
However, there are two things that negate the argument made by Institute for Energy Research.
1. The numbers quoted for radioactive waste generation is an apples to oranges comparison.
The quoted number for Wind Turbines is the amount of waste generated by producing and constructing a Wind Turbine. Once the turbine is constructed, the Turbine should no longer produce radioactive waste over its lifetime. Many different sources claim different values, but the general consensus is that a Wind Turbine should last from 12 to 25 years. While there may be a large upfront cost for the Turbines, there is no more waste produced after it comes online.
The quoted number for Nuclear plants, on the other hand, is the amount of waste produced per year by operating the plant. The plant must continue to produce that waste or it will shut off. The article, by comparing these two numbers, can be translated to the claim that
The amount of radioactive waste generated by increasing the amount of Wind Energy produced by the United States by 13.1 GW for the next 12-25 years is slightly more than the waste generated to maintain current Nuclear Energy production.
2. All radioactive waste is not created equal.
The article uses "tons of radioactive waste" as if all waste is interchangeable. To quote Comparing the Amount of Radioactivity Found in Radioactive Wastes
It should be noted that just as knowing the number of gallons or pounds of a toxic chemical substance is not sufficient to completely predict the hazard posed by the chemical, knowing the number of curies in a radioactive material is not sufficient to predict the hazard posed by the material.
The EPA, in a study titled Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues, says
the radiation levels from waste rock and sludges[sic] associated with the production of REOs range from 5.7 to 3,224 pCi/g.
Taking the high estimate of this number, we can calculate the total Curies (amount of radioactivity) given off by this toxic waste as
(4.7 Mlbs) * (453 g / lb) * (3,224 pCi / g) = 6.659 trillion pico-Curies = 6.659 Curies.
Compare this to the numbers provided by "Comparing the Amount of Radioactivity Found in Radioactive Wastes"
Total curies in a typical spent fuel rod after 120 days of cooling : 1,800,000 Ci
Total curies in a typical spent fuel rod after 10 years of cooling : 130,000 Ci
A single spent fuel rod is several orders of magnitude more radioactive than the radioactive waste produced by the manufacture of Wind Turbines for an entire year.
Note that, even with these numbers, it is still a significant concern of the international community. Quoted from Wikipedia
pollution concerns associated with the extraction of this rare-earth element have prompted government action in recent years, and international research attempts to refine the extraction process. Research is underway on turbine and generator designs which reduce the need for neodymium, or eliminate the use of rare-earth metals altogether. Additionally, the large wind turbine manufacturer Enercon GmbH chose very early not to use permanent magnets for its direct drive turbines, in order to avoid responsibility for the adverse environmental impact of rare earth mining.
There are efforts to reduce the amount of radioactive waste generated by Wind Turbine manufacturing, but the amount produced does not outweigh the waste produced by fission reactions.