Malicious Prosecution Question

My brother had an arrest warrant filed against a bulldozer operator/contractor that stole topsoil from his property to use as backfill for a new house on the neighboring land. The contractor also communicated threats in front of local policemen. When he went to the magistrate to fill out the affidavit, the magistrate told him to place a higher value on the soil taken to "draw more attention" to the case. The magistrate also told him that he was not supposed to give legal advice and would deny having done so. The warrant ended up claiming $1500 worth of soil was stolen. It did not say anything about replacement value which would be more than that. The actual value of the missing topsoil according to local landscapers is around $400 to $500. My brother did not charge the man maliciously but he is extremely worried that he could be sued for malicious prosecution. The defendant was found innocent of that charge and is appealing the charge of communicating threats. Would Malicious Prosecution apply to this case? Is there any reason for him to be concerned? Any help would be appreciated.

Not really--you don't have to estimate precisely for that kind of product.