Another spin on it using isnull in the case:

create table #tmpTST

(

MyBit bit NULL

)

insert into #tmpTST

select 1

union all select 0

union all select NULL;

select

case isnull(MyBit,0)

when 1 then 'True'

when 0 then 'False'

end AS MyBit

from

#tmpTST;

drop table #tmpTST;