These are ill-chosen words. The triple lock is not a "random variation" but a (very slow) ratchet. The main argument against that is that it promises better pensions to younger generations without asking them to pay for better pensions now.
"the generosity of state Pensions shouldn't depend on random variation between three numbers" At our recent event, Ruth Curtice made the case against the triple lock. Rewatch it here ⤵️ buff.ly/LJbSfNL