Or persuade your HR department to just charge you the tax on the benefit of transfering for a lower price. If they do any other benefits that result in people getting P11Ds it should be easy enough for them.
The other route is to persuade HMRC that your bike isn’t worth what they say it is. If it’s had a particularly hard life, takes some photos and see if you can find some ads for similar bikes to back up your claim.
You won’t persuade your HR department to go against HMRC guidance, but as above, there are various ways to reduce the pain.
EDIT having seen your latest:
They’ll be pocketing the difference, I suspect. If you can persuade them to just charge you the tax, bear in mind that they’ll have to pay a bit of Employers NI on it too.
Also, bear in mind that they cannot force you to buy it. I doubt they want the bike, so the first thing to say is “no thanks”.