A siezed jet engine will cause LESS drag than a windmilling one, for all the same reasons as for the windmilling/stationary propeller.
For a siezed engine, there is only the form or profile drag of the engine. For a windmilling fan, it is extracting energy from the airstream to drive the compressor and other engine accessories. That will cause more drag.
If you can get your hands on the Performance Manual for your aircraft (the one used by Performance Engineers) there are two sets of Drag coefficients provided for a failed engine, one for windmilling, and one for stationary. In all cases the Cd for the stationary engine is less than for the windmilling engine. Performance is predicated upon the engine windmilling, i.e. the worst case.
Regards, and Happy New Year,
Old Smokey