Everyone has unalienable rights and one of those rights is the inherent right of self-defense. I have no problem providing defensive weapons to all nations.
Stingers and Javelins are great defensive weapons. Stingers cost about $120K each and Javelins about $175K each. A single used Mig-29 goes for $5-8M depending upon condition and the Polish ones are pretty beat up so closer to $5M. $5M buys 28.5 Javelins or 41.6 Stingers.
A fighter is both offensive and defensive plus is very expensive to maintain. It needs lot of fuel not to mention the cost of armaments, parts, etc.
IMO, the situation is best served by providing Ukrainians with thousands of Stingers and Javelins to defend their country, not fighter aircraft.
https://www.airforcemag.com/polands-new-offer-mig-29s-in-exchange-for-buying-used-u-s-aircraft/
Poland did not specify how many jets it wants in return for its 23 MiG-29s. Commercially-available, used MiG-29s have recently fetched between $5 million and $8 million, depending on their age and condition. Israel recently sold 29 of its early-model F-16s to adversary air company Top Aces, but the price of the jets was not disclosed.
According to Polish government accounts, that country’s MiG-29s are flyable but need a lot of maintenance, the engines being particularly unreliable. Poland’s statement did not mention spare engines nor whether any compatible ordnance for the jets would be provided.