I think that it isnt easy either way. I don't like the way you played the hand before this ... it is unclear from the HH if you are ahead or not. If it were me I would probably call because it is a 20 180, but that isnt really very useful as a general rule. The fact that you can gambol and just open up another if you lose makes these more like rebuys to some extent.

In a more general sence risking elemination with 99 on the first blind level seems idiotic. If you look at it from the prospective of a single elemination mtt playing against a field of idiots than you become much more protective of your chips. I would never let this happen in a mtt I cared about ... good players play small pots unless they have a monster or a monster read. But ehh your question was specific to a 20 180 ... so your probably not a very good player, and your opponents all suck. With that in mind I like a call.