1) UA hasn't gone dynamic yet, so there isn't 375k UA IAH-EZE floating around (realistically there is no UA IAH-EZE in J with a points redemption as of now - that could definitely change in two weeks, but I wouldn't bet on it regardless); I don't see how that would be anything other than AC's own dynamic pricing on AC; no Polaris space available on AC is not a result of AC dynamic pricing, it's a result of UA making way less I space available than it used to (which in this case is something like 6 years or 3 mileageplus devaluations ago)
2) with all due respect, 2017-18 is a very long time ago in all contexts, but Aeroplan has been bought back, reinvented, kind of improved and then devalued over half of that time span, so 60k in 2017-18 doesn't have that much contextual value for 2025