I liked it
I liked it, because it added yet another layer to their relationship, not because I wanted Kane to be hurt by it
See, in MY mind; I'm going like; what the heck does Kane think that he can tell Bellamy that his mother would be proud. Did he know Bellamy's mom THAT well? I had the same problem last week when they were saying a dead person would've been proud. You can only say stuff like that (in my opinion!) if you actually knew the dead person well enough to know if what you're saying would actually be true.
So Bellamy's sitting there, knowing he can't save them, having to listen to them plea and scream over the radio. And then Kane - the one who freaking floated his mom - tells him his dead mother would be proud of him. Well, of course you're gonna be upset by a comment like that. Well, I'd be
What I really loved is how after, at the end of the episode, Kane said "sorry" to Bellamy.
To me, that 'sorry' was not just about Octavia being gone. Not just about those people having died (and knowing Bell couldn't save them). But maybe about his mother. About so, so much more.
So I think Bell lashing out, made Kane say sorry. And that added volumes to their relationship.