If that was how it was meant to be understood, it could have easily been written explicitly by making it a recursive clause. E.g. in the case of my country, article 4 of the constitution says that the first 3 articles cannot be changed; it could have said first 4 articles cannot be changed, thereby making it a legal impasse.
More likely, the authors of entrenched clauses understood that, if it came to that, making that change illegal wouldn't prevent a slip to dictatorship. That impasse would only hinder the honest actors, if in the future there came a time when those entrenched clauses really legitimately need to be changed; and hence that door was deliberately left open.
Sure, if it came to that, judges may still rule your way to slow down the slide the dictatorship, but then the next constitutional amendment would be "all judges are retired, here's how new judges are selected". Or some other legal maneuver. Even the strongest clauses could be circumvented if they have enough support or power, let alone feeble interpretations of implicit clauses.
More likely, the authors of entrenched clauses understood that, if it came to that, making that change illegal wouldn't prevent a slip to dictatorship. That impasse would only hinder the honest actors, if in the future there came a time when those entrenched clauses really legitimately need to be changed; and hence that door was deliberately left open.
Sure, if it came to that, judges may still rule your way to slow down the slide the dictatorship, but then the next constitutional amendment would be "all judges are retired, here's how new judges are selected". Or some other legal maneuver. Even the strongest clauses could be circumvented if they have enough support or power, let alone feeble interpretations of implicit clauses.