Of course it can be changed But why would you like the char to be unsigned (don't negative integers come in handy sometimes?)... And perhaps the range of the data type should be made a little wider. We would have to test how much is required for backward compatability with earlier submissions, but I guess even some custom value like [-2^12, 2^12) is perfectly acceptable from everyone's point of view..
The reason is somewhat different . The trouble is the name of the compiler 'bf2c + gcc': some people are confused and submit C code as BF. Quite naturally a construct like: int a, b[10]; becomes an infinite loop in BF .
Altering / rewriting the compiler would be a good pretext to change the displayed name.