So far one of the four remaining committee members has done this, another is expected to, leaving the decisions of the remaining two to determine whether the vote completes or not.
Are you referring to the "Technical Committee makes decisions only as last resort." paragraph of the Debian constitution? It's a bit cryptic for a non-native like me, so I'm not sure that I'm reading it right.
In this case F (further discussion) is the default option, and this stage in the voting process precedes the casting vote.
I too think it's unlikely that both Colin and Andi will block the decision, but we've known it's likely that systemd will win for some time now. It's still not yet official.
edit: actually there are other possible outcomes, see https://lists.debian.org/debian-ctte/2014/02/msg00309.html