The Dark Millennium game had an imperial titan called Imperialis Annihilatus. It had a massive shooting stat but it could not declare shooting attacks. It could, however, do a bunch of other things. It could counterattack if it was attacked. It could exhaust to destroy a vehicle unit. It also could(with the right dice roll) refresh if an enemy vehicle became exhausted. we have seen some of that game's influence here, so perhaps this are some of the things they can do with titans.
Seems like it, altough I still think that if they where included, payment could only be done by Planet colours and it would not be able to be put into play otherwise. As it could lead to some stupid battle outcomes from Y'varn. Which I personally detest since Ive seen the Y'varn the Black Legion Heldrake a bit to often.