Like with aluminum, this high reactivity is masked in finite products made of titanium, because any titanium object is covered by a protective layer of titanium dioxide.
What is worse in titanium than in aluminum is that titanium has a low thermal conductivity, so a small part of the titanium can become very hot during processing, which does not happen with aluminum, where the remainder of the aluminum acts like a heatsink.
The hot spots that exist on titanium during processing, which do not exist on aluminum during processing, make titanium much more susceptible to reacting with the air or even to starting a fire.
Titanium, even as "commercially pure", has a much higher strength than aluminum, which requires higher forces for machining and increases even more the chances for overheating.