Fallacy identification?

I'm not sure that this is a perfect fit, but ecological fallacy seems to fit here. The speaker seems to be making the assumption that the martial arts experience of knife attack survivors is reflective of that of the general population, but there are certainly scenarios where this would not be true. For instance, if knife attackers were more likely to go after martial artists, and/or knife attacks were usually fatal and martial artists were the rare survivors.

It is a simple non sequitur UNLESS there is context before or after that justifies this claim. There is an implied connection here between being a martial artist and surviving a knife attack.  Even more, that the rate is known and the math justifies this statement. On it's own, it is unclear.

Here is what would make sense....

Data shows that roughly 95% of all people survive knife attacks. Of those 95%, roughly 1% have martial arts training. Therefore, the vast majority of people who survive a knife attack are also not martial artists.

So the missing data is what percentage of those who survive have martial arts training. The original claim assumes "the vast majority" does not, but does not state that anywhere in the argument.

In my quick research, there is no credible data available that answers this missing question. However, it is certainly reasonable to assume that, given only one percent of the population has martial arts training, that the vast majority of survivors of knife attacks have no training.

Summary - while technically this could be a fallacy if it is claimed to be an argument, it is more of an unclear line of reasoning based on an assumed premise that is not stated. At best, clarification is warranted, not an accusation of fallacious reasoning.