There are already some passivetex workarounds in lists.xsl of docbook-xsl-1.73.2 . Unfortunately not all list-item-body items are handled differently for passivetex.extensions set to true. In attachement is patch against basic docbook-xsl-1.73.2 which I'm using for Fedora.
list-item-body handling workaround for passivetex
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PassiveTeX is no longer supported. See previous comment.
It is clear from documentation of passivetex.extensions parameter.