The phrase "it's ok to be white" has implicature (by maxim of relevance) and associations (by how the phrase originated and is used in practice) beyond its literal meaning. You can disagree with making that statement without thinking it's not okay to be white.
What in particular has been debunked, and by what?
> If it was co-opted, then why [...]
I wouldn't say it was "co-opted" - as far as I'm aware it originated as and still mostly is an alt-right slogan.
> [...] then why did 49% of blacks take a neutral to supportive view of the phrase in the poll? Explain that.
Those unaware of the statement's usage, and those who choose to interpret the poll question as asking only about the statement's direct literal meaning, would likely answer supportive of the statement.
A better-designed poll could separate out those two issues, asking about both the statement's literal meaning and what it implies, but instead it's kind of mushed together dependant on how the respondent chose to interpret the question.
> And couldn't that taint the people against the phrase?
In that, you think some people would agree with the phrase when taken with its implicature and connotations, but then object to its far milder literal meaning? Struggling to see what worldview that'd be possible for.
Yes, everyone engaging in populist racism is basically shitty. I don't think that should be a controversial statement, yet there are lots of people thinking that by pointing to the "other side's" shittiness, this absolves "their team's" shittiness.