I think this will send the wrong message about…
That said, if you use a keyword as a Boolean condition, it needs to use snake_case, similar to a well-defined OSM tag value.
So far, intermittent=yes is only documented with respect to watercourses and waterbodies. It’s an unconventional solution, but quite logical. I don’t know of any renderer or router that currently looks for this tag on a roadway, but it would be much more straightforward than parsing a rare condition out of the conditional restriction syntax, which precious few data consumers support.