The figures I quoted are for removing it from those with private incomes (or equivalent assets to generate those incomes without the state pension - because people with drawdown pensions for example can vary their income so an asset test, as in Australia, is also necessary to ensure the type of avoidance that you mentioned it not possible) of over the “moderate living standard” levels set by the PLSA and Loughborough University which are updated with inflation annually: currently £31,700 for an individual and £43,900 for a couple, after tax and housing costs, i.e. all they have to pay from this amount is Council tax, utilities, house maintenance, food etc.
www.retirementlivingstandards.org.uk
This is far in excess of the average full-time UK salary which is £37,500 before tax (so equates to £29,200 after tax and NI, assuming no pension contribution at all). Working-aged people are almost all generally then paying housing costs from this net income, and childcare costs, which retired people do not pay.
As such, this would leave even those who had their state pension tapered away to zero with far more disposable income than the average working person. The “moderate” standard is set at a level to enable purchase of a 3 year-old car every 7 years, spend money on taxis and travel, have a two-week holiday abroad every year and a UK break, pay for streaming services, pay for regular takeaways etc. It would create absolutely zero poverty to stop paying state welfare to such people.