The real question here is about capacity for intelligence. It's by no means ridiculous to say that someone is born with a maximum potential capacity for intelligence, just as we all have a maximum potential capacity for lifting heavy weights.
Whether these potential values are affected by genetic factors is something else again and, as far as I know, unproven. It may not be the case at all. On the other hand, one genetic subset of the human race may have evolved a higher maximum potential capacity than another subset.
If this is the case, it is no different to pointing out that the majority of south east asians are physically shorter in stature than the majority of europeans. As for whether research should or can continue, i say "why not?" If there is a pronounced difference it makes sense that it should be taken account of especially in education.
Withholding evidence for political reasons is possibly the most despicable thing i think of and has lead to massive injustices over the centuries. To indulge in such a crime merely because of current political mores would be an appalling thing to do.