porous line

The audience for the Cultural Revolution’s dramatic gestures was
not limited to young Chinese but extended to include the political
elites themselves. The intensity of the performances helped convey
to wavering members of the elite that they should not resist the
movement. All states employ ritual, and China’s political tradition
is rich in the use of spectacle. Many peasant rebels against past
emperors have worn opera costumes as they present themselves to
supporters of their self-styled new dynasties, suggesting a porous
line between staged spectacle and political action.

In the last sentence, there is a phrase 'porous line'. Could you tell me what it means here? I think it should be a metaphor which likens a social or political connection to a 'line' which I think it maybe a botanic structure, just like the duct, meaning the posteriors, spectacle and action, have interior relation.