Though I'm curious and have yet read the Statement, I do think Keller's could take his own medicine on his speech act criticism. That his concern is or doesn't like what the statement is doing in spite of the fact that he could agree what it's saying.
Keller is essentially questioning the motive of those evangelicals, which included John MacArthur, James White, etc. That in itself is a problem, the trust is lacking. I am almost convinced that Keller thought his movement was the only evangelical movement that focuses on social justice and thus was jealous of those who claim to be on the same page, jealous enough to criticize them.
Interestingly, I recall a very recent conversation I had with Drew, a former Redeemer pastoral staff. I asked him why Redeemer appears to treat Christians as outsiders while being very friendly to "seekers", to which his only response was "it's not about all of that, it's about what's Biblical".
Ah...1 Corinthians 1:12 never gets old. At the end of the day, it's about who pride himself of being better at doing both social justice and the Gospel.