"It is not wise to have the same item for sale on two platforms at the same time; and is in fact against eBay's policies"

I know it's a bit late to comment on this particular post which appeared on Page 1 of this thread, however as far as I know there is no problem with selling on other platforms as well. The only caveat is that nothing you do on eBay in your listings or messages should invite the buyer to make the purchase on another platform. They have to find it there themselves.