gmaxwell has already stated he is ok with causing a network split below 95% just to get his softwork activated
If there is some reason when the users of Bitcoin would rather have it activate at 90% ... then even with the 95% rule the network could choose to activate it at 90% just by orphaning the blocks of the non-supporters until 95%+ of the remaining blocks signalled activation.
You technically need over 50% to activate SegWit via orphaning other blocks. But I agree it would split the coin because you would piss off good fraction of Bitcoin users (lot of individual miners losing money, plus those who oppose dirty methods to achieve something) if the activation goes through orphaning attack.
read my post again .. edited to further clarify
"just to clear the terminology up
orphaning off a block not because its invalid but because of which pool sent it. is controversial because its not an invalid block. meaning different nodes are accepting different blocks. this causes orphan drama (which will eventually sort itself out to one chain with the minor chain unable to sync)
[this is a contraversial fork that just creates orphan drama then settle down as one chain, and minority unsynced from network]
that then [can] lead to needing to ignore the opposing nodes too [if you want the minor chain to start building its own chain without orphaning.. or if the major chain doesnt want to see the minor chain endlessly requesting and rejecting blocks.]
this is not consensus, [nor controversial, this is a intentional split aka bilateral fork]
consensus is agreement to accept the same data and same rules where the majority accept all the valid blocks (without any biased pickyness) leaving the minority simply unable to sync [ignoring blocks and nodes simply due to a 'brand war' leads to an intentional split] "
