It does answer your question. You just don't like the answer, which is that there need not be a metric equivalent when the word does not represent a measurement

It does answer your question. You just don't like the answer, which is that there need not be a metric equivalent when the word does not represent a measurement. Here's another example: what's the metric equivalent of "footing" the bill? The verb "to foot", in this example, has the exact same etymology as the noun "foot", but it isn't used as a measurement. It's like asking what the imperial equivalent is for "the poem's meter". The question is nonsensical, unlike the comment you were replying to. Sure, the comment was whimsical and flippant, but it was based on a legitimate objection: why express the pressure in an incredibly obscure way? The objection has sense, and the joke is related to it. Your knee-jerk reaction to the joke, however, conflates disparate categories.