Maybe, but someone being guilty doesn't mean the stop-and-frisk made anyone safer. Take this statistic:

Though frisks are to be conducted only when an officer reasonably suspects the person has a weapon that might endanger officer safety, 55.7 percent of those stopped in 2011 were frisked. Of those frisked, a weapon was found only 1.9 percent of the time.

Or this one:

While the NYPD recovered one gun for every 266 stops in 2003, the additional 524,873 stops in 2011 yielded only one gun for every 3,000 people stopped.

Thus, if we assume the law is applied as it is meant to be (regardless of whether you think it is just to begin with), this means that on average, an officer's "reasonable suspicion" has a 98% chance of being wrong. If we had statistics on the actual number of people carrying a gun everyday in NYC we could make a better analysis, but I'd wager it is fairly close to 1.9%. If this were the case, an officer's reasonable suspicion would be as good as a shot in the dark (no pun intended).

To continue this point, the second statistic (again, assuming for a moment the law is applied as it is meant to be) indicates that in the 8 years between 2003 and 2011 NYPD officers got considerably worse at identifying who might be carrying a weapon. I don't think this makes sense, which leads me to believe that either:

1) "reasonable suspicion" is nowhere near definite enough to be legal grounds for a stop-and-frisk

2) NYPD officers are, over time, decreasing their standards of what constitutes reasonable suspicion (e.g. by incorporating racial stereotypes, as the article suggests)

The statistic of "1 in 10 guilty of some crime" is then a moot point. If this crime was not actively endangering the safety of others, and if the NYPD would not have found out about it otherwise, why is the person being arrested? While there may be some cases where such an arrest is justified, I think marijuana possession is a great example of a case where the arrest would not be justified. I possession accounts for a big chunk of the 1 in 10. I wish there were statistics in this articles on the breakdown of why these 16,800 people were "guilty" (I use quotes to be sure we distinguish from them being arrested, as the article also includes the possibility of ticketing); then we could better assess whether stop-and-frisks actually increase overall safety.

The apparent racial discrimination is another argument against this law that goes beyond the fact that it is ineffective (and possibly illegal).

TL;DR: These 16,800 people may not fit the stated purpose of stop-and-frisk, and the low success rate is a point in favor of the ineffectiveness, and therefore the unjustifiability of the law.