I've seen barely any 40k mods shut down by GW. Most of them end up die out due to the lack of support necessary to convert something into the setting since is very defined in terms of style and there are few things that match it without requiring a total conversion.
And as for the reason that Heresey: Tactical Deployment was most likely shut down is that it is basically a free version of Space Marine which has yet to have even been released. While it's sad it was shut down it would honestly have been incredibly stupid for Games Workshop to allow it.
KaboomMaster
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