Lithium batteries DO hold charge longer than many other types, thats one of their advantages. The other downside is they tend to have a short shelf life whether they’re used or not.
I think you may have these things mixed up a bit ¯\_(ツ)_/¯ Sparing everyone the discussion on various battery chemistries and borrowing from Ballistic's FAQs (since they're probably the most popular/reputable lithium moto battery manufacturer out there)-
-EVO batteries are more efficient than a lead acid battery. EVO batteries have a static discharge rate of only 10% per year. A lead acid battery self-discharges at a rate of roughly 1% per day. An EVO Battery has a cycle life of more than 2000 cycles versus a conventional battery which has a cycle of roughly 600 cycles. All of this means your battery will last longer.
-Although EVO batteries have incredible energy density and they can burst more cranking amps than a conventional lead-acid of similar physical size, they have less amp/hours. Amp/Hours is the ability to deliver a small amount of power over a long period of time. This means that if you typically use electrical accessories when the vehicle is off, a lead-acid with more amp/hour capacity might be a better choice.
So, yeah, when the battery isn't connected to anything it'll hold a charge longer, but that's pretty much meaningless if they're in a bike that has any parasitic draw. It does mean that they can be left sitting uninstalled pretty much indefinitely, and why the replacement lithium battery I got in 2013 is still in great shape despite spending most of it's time on a shelf. That moves us on to the second point, which is the energy capacity (not how much energy they can deliver for starting) of lithium batteries vs more traditional chemistries...which is substantially less. Which is why with a bike with parasitic power draw, an unattended lithium battery can easily be taken below the ~10v minimum, rendering it useless, and an AGM battery would take much longer to discharge, and be more easily recharged.
Mostly talking semantics though 😂 Like I said in my first post, stock S1000RRs usually have very little parasitic draw and batteries, AGM or lithium, can be left for quite a while without worry.