So look no further for evidence of accelerated tectonic movement.I always saw exponential decline in volcanic evidence,now they have found evidence of the tectonic plates themselves moving very rapidly.
The science daily article states that these are plants and animals from lake sediments. That these animals died off 2-3 mya. It only hints at these animals dying off due to changes in their enviroment. Maybe the Earth and Planetary Science journal this article sites may elaborate. So as with all of palentology, dates may be revised. It is not evidence of rapidly moving tectonic plates, only a revision of when the plataeu has moved to an elevation high enough that these organisms could not survive. It may not even affect when the begining of the collision of the two plates occured(according to wiki about 70 mya). It also does not change the marine strata that have been found folded into the mountain range. It certainly does not call into question dating methods used the way you suggest(that radiometric is fundamentally wrong). As Dr. Adequate points out there is much debate over himalayan orogeny due mostly to the lack of research so it is common sense that as new evidence comes out dates will be revised.
One last point, if you look at Mt. Everest 8848 meters above sea level(wiki), and divide by the current rate of elevation increase,.005meters/year(wiki), that would have only taken 1,769,600 years. This is certainly flawed since the rate of elevation increase is probably not constant and the height did not start at current sea level, but it does give you an idea of gradualism.