This will be of little use for the Ukrainians. If they (legally) can't work in the European Union, then what is the use in having a visa free regime? I assume that a lot of them will start working illegally. Some will apply for the refugee status as well, especially those from the Donbass.
And what prevents to do that now? Visa-free regime need more Europe than the Ukrainians. Those who want to illegally work in Europe for a long time and no working visa this is not a hindrance.
Ideally, the European Union should give preference to Ukrainian immigrants over the Muslim rapefugees from the Middle East and Pakistan. But for political reasons, they refuse to do that. Let's wait and watch.