I didn't notice any mention of how much carbon you anticipated using... well, don't use much, a spatula tip, 1/4 of a ml type volume, bugger all really. Use less if we're talking about less than 50ml of solvent with dirty alkaloids in it.
The best thing for removing the carbon is the ol' charmin filter, two passes always does the trick. I can't see the carbon dust staying inside your little teabag myself.
I'm not sure if carbon is any use here anyway, the two places the colour comes from in e/rp/i are the iodine, which a nonpolar solvent will wash out, and from the iodoephedrine itself, which you shouldn't discard adsorbed onto carbon, you should separate it properly and maybe put aside to add to another reaction later.
Decolourising the material only really makes sense in the case of organically extracted substances, as there can be inactive amines that have colour coming across (such as the yellow stuff in mimosa hostilis root bark extracts) Even in those cases, the carbon is feeble in comparison to recrystallisation purification.