K shaped economy with increasing expenditure means the wealthier increase their spending as a portion of the economy and at an absolute level. It is not interpreted as the polity doing well - if anything, it is cause for concern.
The retired middle class boomers I know are completely outside the business cycle.
While I don't think they have enough to really be considered wealthy, they have no mortgage payment, a social security check, a pension and most have a 401k.
The business cycle will not change their spending one bit.
It may, a bit. If the 401k is in the stock market, and the stock market is down, their total visible money is down. That tends to decrease enthusiasm for spending.
It may also affect it a lot. Retirees I know have a retirement plan that involves their retirement accounts being at a specific level at the end of each year. If their accounts are over that level because the stock market had a good year, they consider it funny money that they're allowed to spend.