I would have thought two would be safer for a complete rejection as whilst those reasons could be valid, all the other core team members would take those reasons into account but they can still make concious decisions as to whether they agree those reasons are enough to stop the progression of the PR.

This is a problem with the PHP core and that's that because it requires a 2/3 majority, major things rarely get through as they'll get over 50% but not over 66% as there are valid technical reasons for a no vote, it's just others view the weighting/importance of those reasons to be different.