Quantum Contradictions 4: Helium isoelectronic sequence

The postulated ground state of 2-electrons atoms/ions according to the NIST Atomic Spectra Database,  is the 1s^2 state of the He isoelectronic sequence (2 electrons with opposite spin and identical spatial wave functions with exponential decay away from the kernel). But the energy of the postulated 1s^2 state is not the observed energy as shown in the following list with the experimental value (in eV) first and the larger energy of the 1s^2 state in parenthesis:

1. He : - 79 (- 74.80)
2. Li+ : - 198.09 (- 193.80)
3. Be+2 : - 371.60 ( - 367.20)
4. B+3 : - 599.58 ( - 595.00)
5. C+4 : - 882.05 (- 877.20).

It appears that in the true ground state with energy in accordance with observation, the two electrons are separated into roughly speaking two half-shells together creating an electron wall shielding the kernel. The appearance of such a wall could possibly explain why a third electron will be pushed away into an outer shell without resort to any two-electron Pauli exclusion principle.

The fact that the postulated ground state in the He isoelectronic sequence is not the actual ground state gives the postulated quantum mechanics support of the periodic table, based on Hydrogenic orbitals combined with Pauli's exclusion principle, a bad start with possibly catastrophical consequences concerning scientific rationale.

PS Pauli's exclusion principle is an ad hoc assumption which serves to eliminate e.g. a 1s^3 state of Lithium with 3 electrons sharing a 1s state, which shows to have energy smaller than that observed and so must be unphysical in some sense. If already the 1s^2 state is unphysical, this may as suggested prevent the appearance of a 1s^3 state without any ad hoc exclusion assumption.