In recent times I've begun to feel that this
"not celebrating against the ex-team" is kind of silly. The reason being that it's fake. Everyone is happy when they score a goal for their club, even if it's against your former one that you love.
I know it's about "showing respect", though, but come on. We (fans) are not that important

And the clubs themselves can definitely deal with it; for them this is all about finances / sporting results.