Doesn't matter what they testify, the burden of proof is on them at this point to prove they would have done this anyway, independent of the unionization effort

Doesn't matter what they testify, the burden of proof is on them at this point to prove they would have done this anyway, independent of the unionization effort. Which, given that it was suggested to them by the union-busters they hired, is going to be difficult. The test for such a burden shift is 1) effected employees took a protected action 2) the company knew about it 3) the employer didn't approve of the protected activity. 1 and 2 are trivially proven, 3 is proven by the company hiring union busters.