I'd just like to mention, that the same rule which limits the skimmer base removal to the effect of "immobilised" and "wrecked" results also says in the end:
"Note, that it is not permitted to remove the flying stand other than in the two cases above, as normally skimmers cannot land in battle conditions."
That is the general rule.
The codex says:
"Tau vehicles are fitted with basic landing gear in case they should suffer malfunction. In any turn that the vehicle does not move, it may choose to no longer count as Skimmer until it moves again. This benefit does not apply to the first turn of the game".
This actually doesn't mention landing, though I think it is reasonable to assume that is what the rule describe.
Ability to land is thus defined in the codex as exceptional ability of Tau skimmers (result of the particular Tau design policies), and thus it exceeds the "normal" conditions
BRB describes. As such it can be understood as specific allowance to remove the base to land the vehicle.
I'd call it common-sense interpretation of the rules.

At the very least, if your opponent feels very strongly against removing the base, you may still decide to stop counting as skimmer without removing the flying base (nothing prevents you from doing that). I'm not sure what would be the benefits though.
Personally I do not see the
BRB rule from the 5th edition as cancelling the functionality of the Tau landing gear as described in the Codex.
It's another matter that the ability to land is extremely situational and has little practical value, especially in the current edition.