Barely, because the estimates of dark matter are not sensitive to the IMF, they use (a) the dynamics of objects in galaxies to estimate the total mass of that galaxy, (b) observations of kinematics in galaxy clusters that depend on the total mass present, (c) measurements of the cosmic microwave background combined with measurements of primordial abundances of deuterium and helium that directly give the fraction of dark matter in the universe.
While the latter is really the gold standard and doesn't depend on the stellar IMF at all, the first two techniques do to some extent depend on some assumption about the stellar IMF through the stellar mass to light ratio. This is in order to separate the inferred total mass distribution into a baryonic (stellar) and dark component. However, although M dwarfs contribute almost no light (compared with higher mass stars) and are very common in the solar neighbourhood, they also contribute little mass compared with the overall total of all matter, so the results are insensitive to the numbers of M dwarfs unless they are wrong by orders of magnitude.
A further point to consider is that because all the low-mass stars ever born are still alive, the IMF that is has been previously estimated and used for low-mass stars would be the time-averaged IMF. But that is the correct thing to use when calculating the stellar mass of the average population in a galaxy. What might be affected is how much baryonic matter was made into stars at what point in the past - i.e. the star formation history.
I will read the paper with interest and come back to this. Estimating the ages of M dwarfs is extremely difficult.