Sorry, the fitment list is TYRE manufacturer's, not BMW. My error.
Put K1300S on the Mich site and it only shows sports bike tyres, eg Power RS, Pilot Power 3 etc. The shop phoned Michelin and they agreed with the website info.
They seem to see the K1300S as "hypersports" or something...
The Bridgestone S21 is a supersport tyre so won't last as long. Their new ST tyre is the T31.