It looks as though tensions are rising in Malaysia over the use of the word "Allah" by non-Muslims. The Government had banned a Catholic newspaper from using it in its Malay language editions, however a recent court decision -which the government has appealed- deemed the ban as unconsitutional.
There are sometimes good reasons to frown upon the use of certain words by members of outside groups. You may address your partner by saying,"hey, sexy". There may be fisticuffs if I addressed your partner in the same way.
I don't think that reasons analogous to the above would hold in this case, as to my knowledge "Allah" is a term that was borrowed from Arabic by Malaysians in order to express the relatively new concept of a single deity. Apparently there are concerns that if Christian groups are allowed to use the word "Allah" they may attempt to draw people away from Islam. This position may be a reaction by more conservative Muslim groups who believe that their interests are threatened by what they see as the encroachment of a more secular vision of Malaysia of the kind being espoused by the coalition of opposition parties.