Nope, sorry, that is simply false and I explained the difference in previous posts. You can read what I wrote, but since I know you won't, I'll explain it again:
1. Ted Cruz was born in Canada. John McCain was born in the Canal Zone. In this case, the debate is over their eligibility, not a lie made up about their birthplaces. Obama was not born in Kenya.
2. Unless you can prove that the questions over Cruz's and McCain's eligibility were due to their race (and there is no evidence that it was), racism is not involved. It is petty and political, but their eligibility was not questioned because they are white. If that were the case, then yes, it would be racist.
3. Birtherism was spawned by the same people who consistently accused Obama of being a Muslim, emphasizing his Arab middle name, and a clear case of "othering". Obama was black, had a "foreign"-sounding name, ergo, he's a foreigner, and a lie was made up about where he was born. The fact that you see the debate over Cruz and McCain as being identical to the racist lies about Obama only reveals the lens through which you see reality (a foggy, scratched lens at that).
Ya, I get it. You just doubled down on how I said you understand the world. When the "same people" (i.e. Trump) call Cruz a birther it's driven by legit debate and when he calls Obama a birther it's because he can't control his racist impulses.
The alternative explanation is that, in politics, everyone smears everyone. Put another way, it seems unbelievable to you that people could smear Obama without being racist. Hey, maybe Shiller is leaving Twitter because deep in his heart he hates South African Canadians?