"Since it is unanimously agreed by all Poskim that legs must be covered so that they do not attract attention, skin-colored tights are obviously assur, as they attract attention and defeat the purpose of covering the legs."If you read the sentence a few times extremely carefully, you might note that he does not say that all Poskim unanimously prohibit flesh-colored tights. Rather, he claims that they all unanimously agree that X is true, that "legs must be covered so that they do not attract attention." And the "obviously assur" part is his own extrapolation based on his understanding of reality and how it interacts with X. (And one perhaps senses that he was deliberately careful with his language to convey the impression that they are unanimous about Y, without actually making this false statement.)
I am not going to look into X in this post, to see whether poskim are indeed unanimous about X. Let us just accept that as a given. But do poskim unanimously agree to Y, that therefore flesh-colored tights are obviously assur?
In fact, there is a major posek who offers a reason for the practice of those who are makpid that their daughters and wives wear stockings, but are not makpid that they not be flesh-colored. (The questioner was asking about sheer stockings, but the posek moved the question to flesh-colored stockings.) This posek was Rav Moshe Feinstein, in Igros Moshe, Even haEzer chelek 4, siman 100, seif 6. A while back, I translated this seif on parshablog, and so it is available here.
If so, Rabbi Falk cannot claim that all poskim are unanimous about Y.
Now, perhaps Rabbi Falk was simply unaware of this teshuva. After all, it is one late seif in a larger teshuva. However, we know that Rabbi Falk is aware of this teshuva. On page 329, where he introduces the entire issue of tights, he mentions this teshuva explicitly, and claims (or seems to claim) that Rav Moshe is requiring tights because it is an area which is usually covered. I discussed Rabbi Falks characterization of the teshuva in this earlier post -- I am quite unhappy with his characterization, but read that post and decide for yourself.
Regardless, Rabbi Falk obviously knows about the existence of this teshuva from Rav Moshe. And the very purpose of that teshuva was to give a reason in favor of flesh-covered tights. To not mention this teshuva here, where it is most directly relevant, seems to me like misleading by omission. And especially where he leaves it out and then appears to state that it is the unanimous position of all poskim that skin-colored tights are forbidden.