The three redirection scripts included with the UBB.threads importer archive (threads_import.zip) all have the same basic coding flaw:
if ($search_friendly = 1)
The test will always succeed no matter what value for $search_friendly appears in the scripts. The line should read:
if ($search_friendly == 1)
The "readme" that comes with the scripts should also note that the variable needs to be set to a value other than 1 for those who do not wish to use search-engine friendly URLs.