This particular pearl clutch is even stupider than usual when it was already explicitly not apples to apples. For a time-dependent load you have the other 90% of the budget for the nuclear reactor to figure out storage (or to meet daytime loads or flexible loads).

This comparison is fuelling an SMR you already have vs. turning it off but continuing to staff it and pay for the back end of the fuel cycle as if it were running when it's sunny and running solar instead.

If the marginal cost of the SMR is higher than the all-in cost of solar, then it is always optimal to build the PV array (so long as the grid is not saturated with solar) even if you already have surplus nuclear. So the much bigger portion of the SMR cost (the reactor and fixed O&M) has to justify itself just on the loads that solar cannot feed.

Of course this is not true everywhere yet (and this does not apply to more efficient large reactors), but the niche for SMRs is smaller than traditional reactors and shrinking.