No, sorry, but if the stem is girdled, bark removed all the way around, there really is nothing you can do. Just wait, and see if it pushes up new growth. If your plant had been longer established there would be a good chance it could regrow from the base, just one year planted and I don't think the chances of recovery quite as good. Possible, but not good.

Maybe buy the man a wheeled rotary edger, get the string type away from him ;)

I noticed today while digging out weeds around it that there are tiny leaves coming up around the bottom of the plant so hopefully I can keep the slugs back long enough that the plant can come up from the bottom

Why weed whack around a tree or shrub in the first place? Remove all the vegetation a safe distance from all your desirable plants and only weed whack what creeps past this border.

On another note, if the tops were not totally dried out you could use those for propagation.

Some low green fencing that will be invisible under the branches but will stop the weed string might help. Another thing to use is a rock (or several) place where it will protect the main stems but not show (assuming you don't want it to).

I pull the weeds back 6 inchs or so from the base so there was no need to get anywhere near the the base of the plant. He just gets in a hurry and more or less waves the weedeat back and forth on the hill side. That hydrangea bed is on a fairly steep slope were our upper driveway was cut into the hillside. This last incident has made me decide to move plans forward to put a rock retaining wall in so I can multch the hydrangeas. The steepness prevents me from multching right now.