Well I would guess he has, and having seen as I have after I just went and perused the top 10 or so forums they are all in agreement that NO one cannot travel with such a bike/battery - so he is hoping that someone here has a more clever answer. Furthermore, tmac is not the clever person to argue the "but you allow scooters and other mobility devices" and it seems that unless you show up being very old, riding a scooter or are missing a leg or whatever, no airline, especially it seems BA is going to let you on, most airlines say something like , "You can take a mobility scooter battery but only if you’re a passenger “whose mobility is restricted by either a disability, their health or age, or a temporary mobility problem”. So while TK is not as verbose and explanatory, they are not going to allow it, and probably neither is BA
This reminds me of emotional support animals, originally so that certain people who needed their animals could bring them onboard, which then turned into a "everyone can bring everything onboard and save the kennel fee!" and now has been curtailed. It is estimated that there is one fire every ten days on planes due to -ion batteries, and they are mostly small reasonable ones. There is a reason for this, and even if your bike had a removable battery, you could not carry on a battery of this size, which is why some people use stackable removable where each unit is just under the threshold.