A small but savvy minority of GLB people recognize that GLB causes are not the same as transgender causes. The former has to do with sexual orientation, the latter has to go with gender identity regardless of sexual orientation. People who support this view do not think that transgendered people should have no rights, but simply that they have nothing to do with GLB rights, and therefore oppose the use of the term GLBT and the countless other variants with all sorts of different letter combinations on the end.
The most outspoken proponent of this view is John Aravosis. He has pointed out that GLB activists have been trying to pass the Employment Non-Discrimination Act (ENDA) for 30+ years, and just when it actually had a chance of finally passing in 2007, they tacked on the T to make GLBT, and then it had no chance of passing. Thus, the initialism GLBT (and any other unnecessarily long variant) has actually held back GLB rights.
Person B: No, I support GLBT minus T causes.