I think you could sign Pinto for 500k less.
Unless there's been some announcement I missed, Brassard is not coming back as a player. That was a serious injury to end his season and he'll be 36 in September.
And why sign Comtois just to leave Greig in the AHL?

I highly doubt the Sens or any team signs Brassard, he most likely retires

I'd be ok with signing Comtois. I'd then have :

Tkachuk - Stutzle - Giroux
Greig - Norris - Batherson
Kubalik - Pinto - Comtois
Joseph - Kastelic - MacEwen

I wouldn't sign Comtois until after camp.
Plenty of guys in our system who could potentially step into the bottom 6 somewhere:
Smejkal, Highmore, Sokolov, Crookshank, Ostapchuk, Reinhardt... and there'll be decent players hitting waivers too.

Comtois could actually be a 2-way force on the bottom-6 if he would finally forget about trying to be a scorer.