[en] en-US-GB.txt: should the rule ignore case?

File en-US-GB.txt contains the word pair behavior;behaviour

Check text in AmE with this line: Behaviour, behaviour

LT gives these messages:

Starting check in English (American)...
1. Line 1, column 1
Message: Possible spelling mistake found (deactivate)
Correction: Behavior
Context: Behaviour, behaviour
2. Line 1, column 12
Message: Possible spelling mistake. 'behaviour' is British English. (deactivate)
Correction: behavior
Context: Behaviour, behaviour

Should the rule that uses en-US-GB.txt ignore case?