Why would it drive wages down? The less desperately that workers need a job (due to universal basic income), the more they can demand, assuming they also have skills that fill the employer's need.

The trick for this to work is that the UBI has to really cover a lot of basic needs.

Overall, this works better for lower skilled workers than it does for higher skilled and higher paid workers. But it could also make sense for people staying home to raise their children, a job which is not compensated today.