From your link: "Although CO2 gets most of the attention, it accounts for less than half of this warming. Two-thirds come from non-CO2 forcings." So it's much over 5%.

All of transport sector emissions makes up 20%. The other subsectors are decarbonising, but there's no tech solution in sight for air travel in the needed timeframe. And air travel is growing alarmingly quickly (doubled between 2006 and 2019).

All the individual slices of the pie we can tackle are pretty small, aviation is one of the bigger ones. We can't keep subdividing and then concluding for each one that it's too small to matter.