Man look, Hickman is a Doom fanboy who had Doom punk Thanos like a lil bytch because
who else would he have make Thanos look like a little bytch?
He had Doom choke the shyt outta PhoenixClops because...
of course he would have Doom choke the shyt outta PhoenixClops
He had Doom be God Emperor Doom and out-finess the Beyonders and become all powerful all everything... because fukk all you other characters in the Marvel Universe
With his only weakness being Susan's wet wet because the only person Hickman is a bigger fan boy of than Doom, is Reed Richards. And Reed's bytch (Susan) apparently has that god snatchin wet wet like she must've been in the hyperbolic time chamber doin kegels for days
So yes, killing Namor was Doom's right and Doom's right alone, because
who else would be more deserving of that?