Moriarty seems to want to have Porter killed because Porter was "clumsy" in revealing the connection between the house where Adler was being kept and Porter. The clue that revealed that was the rare paint. With the Moriarty reveal this part of the plot just doesn't seem to hold to me. You can't order the purchase of a rare paint and be disappointed that this paint was ordered at the same time - that doesn't seem consistent with the intelligence of the character.
But you can expect your henchmen to be more careful in acquiring items that could be traced back to them, and ultimately to you.
Sorry, late to the party, only just caught up. Whew, that was quite a twist on Holmesian canon; and no, this isn't the last of Moriarty, no doubt she'll come up with something to get herself out, whether some legal ploy, or straight-up jail break.