I'm inclined to agree, actually. I think he'll have a hand in defeating/bypassing the Buster Call, but him destroying the whole thing is a bit… much.
Of course, they could always slip by the Buster Call, but what fun is that?
Spandam is plenty enough IF he turns out to be powerful enough. His sword has one devil fruit, and if his shoes turn out to be more than just elephant themed, then this could get interesting.
I can already picture a pair of attack elephant bodyguards, one is a sword that ate an elephant fruit, and one is an elephant that ate a shoe df. So you'd have a Sanji and Zoro in elephant form defending Spandam.
Whatever the case is with Spandam, I think hes actually going to be one of the toughest CP9 members to bring down - his actual strength may be weak, but he made a boasting comment about DF technology I do believe, so it may turn out that hes geared out the ass in DF assessments. This would also fit because Ussop is a relatively weak physical fighter whose very very tricky and versatile, and Spandam would basically be the same deal except evil.
Plus he and Lucchi are the heads of CP9 - Spandam is the head, but Lucchi is the strongest member, so the sort of quasi fit in the with the old Luffy and Ussop arrangement where Ussop was always trying to say he was the captain (even though its really Luffy) - Ussop gets to prove his own against the real "captain" of CP9.
I mean, Oda wants to make Ussopp into a "legendary hero", and Spandam is just the perfect peice of villain slime to bring down in both importance and evilness, it works quite nicely.