I can only guess it's all a part of our new woke and PC times:rant:
You can still buy a stock of old-formula Tabac on many sites - just make sure before they deliver they haven't swapped it at the last moment. But in the future you are definitely correct: many wet shavers like myself will not buy Tabac any more. But on the other hand, many vegan wet shaver will start buying Tabac - so I'm not sure their balance will be negative.
In any case, the market for this product is so infinitesimal they will not even feel the difference in their overall yearly income either way. If removing tallow will enable them to advertise that they made their entire line of products (AS, EDC, etc.) "cruelty free" - or any other such PC phrase - this alone can probably justify the move for the marketing department:gaah: