In this case the goal of stimulus is inflation and it isn't enough to repair the economic disruption.
Despite the sharp and historic deflation this is not unusual though. Pandemics are historically known for economic deflation. Europe experienced a devastating pandemic about once a century for more than 10 centuries in a row yielding plenty of economic evidence to this.
The most important thing to learn from this is that a sudden economic deflation hurts poor people and corrections insufficiently help poor people. Wealthy people are not directly impacted, at all. Attempting to correct for that difference with an economic stimulus, such as giving poor people cash, does not at all balance that disparity.
If anything this current pandemic illustrates that a UBI is an insufficient control for balance. Instead of focusing on what to do about poor people if the goal is to balance the disparities of wealthy people against poor people then wonder what to do about wealthy people. Tax the shit out of wealthy people and use that increased government revenue to grow the economy directly in ways only business can: increased infrastructure (there is more to that than just roads and telephone poles).
As for taxing wealth I am a huge fan of a complete estate tax and not a huge fan of income taxes. Take everything greater than $10 million of estate value when a wealthy patron dies.
Australia currently has a program where anyone impacted from the effects of the pandemic, receives $1,500 a fortnight- and yet is experiencing deflation. The very fact of this debunks your argument, as it is a significant portion of the population who is now receiving a cash injection. This money is not exclusively for rent, nor is it tied to food stamps; it is $1,500 to spend as you wish.
Further, The Reserve Bank Of Australia is in favour of these payments. And it's also worth noting, many economies have an inflation target of about 3%, which indicates that inflation is healthy and to so staunchly avoid anything that may affect inflation is a fools errand.
Regardless, please read more than a wikipedia article before holding such a strong opinion. The other commenter called you out for being lazy, and I wholeheartedly agree with them.