I highly doubt that a budding bioterrorist organization would even risk allowing Chris to "work" for them... his heroics in the RE universe is too well known. Ada, on the other hand, is another story.
I think it is laughable that people think Capcom is being serious/honest when they say that this is Chris Redfield. They're not gonna give away the "twist". They want us to speculate like they did with Ada in RE6.
It's not Chris- but if it is then I completely agree with @Turo602 on that being the dumbest decision Capcom could make for his character. If it is Chris then there is some serious mind control crap going on here... perhaps Wesker is back and with his best man (who looks fugly now).
mind control you say? thats actually not a bad theory