It's a good point but back in March the coronavirus was less understood. We didn't know that they were less likely to spread outdoors. We didn't know if the virus was really airborne or not. We didn't know masks helped because they were commonly spread by droplets. (Ok, a lot of the world did, but America didn't.)

If road constructions had to be done in groups (likely?) then it was putting construction workers in front of an unknown set of risks. I think we understand all those things a little better now so in retrospect it may have been a good idea.