Ah, so everytime one of badfarmer's self proclaimed educated soccer moms complains we should change what we do....got it.  I'm not saying your scenario doesn't exists but it isn't something everyone has to deal with.  (editted - missed his IL location, so I would say for him it may be an issue or at least a higher % of likelihood)

If he is going to spread on frozen ground and he routinely gets big rains while the ground is still frozen then no he shouldn't do it.  IF his ground frozen enough to run, and when it rains amounts are light why the heck not.   Bare ground will thaw w/just some sun anyway and a rain shower will likely dissolve the material allowing it to attach to the soil.