The only possible culprit in the ruling would be the 3rd, reading “Convey a clear, simple meaning. Clear and simple messages are easy to read and comprehend with only short glances away from the roadway, resulting in minimal visual and cognitive distraction from the driving task. The use of witticisms, colloquialisms, and popular culture references that target or are comprehended only by a limited segment of the population is not consistent with a clear, simple meaning for all. Instead, these messages rely on hidden meanings or targeted cultural knowledge to understand the message. Similarly, the use of newly coined terms (neologisms), words combining the meanings of two words or blending of sounds (portmanteaus), metadata tags ("hashtags"), electronic shorthand ("Internet slang"), and other forms that do not use conventional syntax do not convey a clear, simple meaning to many road users.”

If anything, the witty sayings on the Maine CMS system fulfills all of those requirements. Quick read, no slang, easy to understand and translate into roadway directions. They are also, besides in your case, something that is eagerly anticipated by drivers and passengers, rather than ignored. An example of an ignored sign is “Yield” or “65 mph”. You should stop ignoring the changeable signs. They are there for a reason, and your judgment of their efficacy is not a condemnation of them, but rather, of you.