It does not say you should be intolerant of the intolerant while they’re minding their own business
it is a fallacy that the intolerant mind their own business. being intolerant is, itself, an active state, not a passive one, and one to be actively resisted. being intolerant involves choice, a choice to be intolerant. there is no “minding one’s own business” in being intolerant, as being intolerant necessarily involves minding the business of others and then making the choice to react to it.
so your argument is, itself, spurious for it is fallacious in its foundation.