This is probably technically accurate however it’s a very unintuitive player experience. When you have ‘one-click garrison’ enabled, not only does it prevent you from garrisoning in buildings (which makes sense) but also loading onto transport ships, which doesn’t feel like ‘garrisoning’ at all, even though the tooltip does say ‘Unload garrison’.
Would recommend making transport ships either not behave that way, or adding is as an additional options to explicitly say it. Or at the very least, a hover-over text to the one-click garrison that will explain the scope of the effect.