Sure! Competition is what forces people to strive for excellence, right?
Provoking in thought, I hope! :)
I disagree, though. If he had zero respect for you he probably wouldn't link to the original mod or give you any credit whatsoever. You've done a grand job with blastcore and you've made a good name for yourself so I understand where your support comes from, but I feel you shouldn't be so opposed to outside intervention.
I honestly think that, courtesy aside, this isn't that big of a deal. You've created a mod - someone has made a submod of it in your absence, to cater to the community's wishes.
If anything, this should be a great motivating factor for you to push out your update. Or perhaps you two could collaborate and create an even better mod at a much faster pace? There are a lot of possibilities.