This is a good point! I've created a ticket on the github issue tracker for the issue. It should be a quick fix if you care to submit a patch, otherwise I will probably not get to it until after FOSS4G.
https://github.com/dwins/mapnik2geotools/issues/14
On the topic of PostGIS, I've been working on some improvements in preparation for FOSS4G (where I'll be presenting on Mapnik2GeoTools) and have a few enhancements in the pipeline. While working on them I've been thinking hard about how it would be useful to include the PostGIS driver with Mapnik2GeoTools so it can connect directly to your database and create the tables it needs (and also allow you to use VIEWS instead, which are slower but can be created much more quickly.)
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David Winslow
OpenGeo -
http://opengeo.org/