Not only do I disagree with the description of Big Bang Theory as "nerd blackface" (and, in fact, find that description offensively trivializing of the actual nature and impact of blackface, but that's getting tangential), but clearly the description is more applicable to Scorpion, in which, unlike Big Bang Theory:
1. All the hyper-intelligent characters that are part of the main recurring cast are male (BBT has a 4:2 gender ratio in the characters portrayed as unusually intelligent),
2. The one female character that is part of the team with those characters is a female who is explicitly part of the team to, as described upthread, "lubricate their social interactions." (BBT has a range of social ineptitude among the intelligent characters, including one of the intelligent female characters as particularly socially inept.)
3. Is, rather than a deliberately and overtly ridiculous sitcom, a drama billed as reality-based.
Firstly, blackface used white actors painted black, unnecessarily. Comedy cannot use real nerds, because real nerds cannot act. Non-nerds depiciting nerd characters are used for the same reason that, in acting, non-surgeons portray surgeons, non-pilots portray pilots and non-US-presidents portray US presidents. Blackface is offensive even when the actual portrayal the black characters is balanced, simply because of the discrimination against black actors which prevent them from getting the roles.
The nerd stereotypes in BBT are not single-faceted, and they are not offensive to nerds. In fact, nerds love BBT. Most of the characters on BBT are "real" in the sense that people can relate to them.
Something that might satisfy a reasonable definition of "nerd blackface", if there is one, might be, say, The Revenge of the Nerds (1984).
1. All the hyper-intelligent characters that are part of the main recurring cast are male (BBT has a 4:2 gender ratio in the characters portrayed as unusually intelligent),
2. The one female character that is part of the team with those characters is a female who is explicitly part of the team to, as described upthread, "lubricate their social interactions." (BBT has a range of social ineptitude among the intelligent characters, including one of the intelligent female characters as particularly socially inept.)
3. Is, rather than a deliberately and overtly ridiculous sitcom, a drama billed as reality-based.