The sea slugs pass their digestive systems, we then eat the sea slugs sans digestive systems.
There is a culinary process between the passing of the digestive systems and the eating of the sea slugs, though.
You make a good point, QLFixBoy. Perhaps my experience makes it seem so obvious...
Indeed, the previous strip dose not necessarily help explain this one, but notice the trend: it's not uncommon for Scott to develop a theme over three or so days, where we understand the whole meaning at the very end of the week (remember the strip where Dilbert is accused of murder and gets defended by Dogbert and finally gets freed from jail back into his... 6x6 cubicle, with the remark "I'm so happy to be free" or something like that)
About your last point - that the audience may revere him as an expert... I totally disagree with your assessment that he should not fear public speaking because "his audience will unquestioningly revere him as an expert." He is absolutely right to fear it, PRECISELY BECAUSE his audience will unquestioningly revere him as an expert!
Believe me, I KNOW!!! Every 'expert' learns it at some point in their career or another. Those who haven't, simply haven't been there long enough.