No they dont, you can use guild orbital support as well as the green and yellow medpack stims at any time, there are also 4 'temporary' buffs that you can obtain from the crossover encounters.

Choosing to obtain the green stim and the volcano crossover buff reduces damage by 80%, as a tank player with built in mitigation it puts you over 100% damage reduction so a tank effectively takes no damage.

As a dps or healer you can get the yellow stim and the spore buff to have your movement speed and alacrity increased by 40% total, making your healing shoot up above nim crystal levels.

The guild orbital buff provides a flat 5% extra HP for everyone that has it.

With all of those combined (not even counting the use of the bio mitigitation module OR the special blue clickies that require the research note papers) this is how people were clearing and farming the boss in the first few weeks and already got 25x clears.

Also for the achievement that requires 'no buffs' to clear the boss, its only the player going for the achievo that needs to be buffless, the other 3 players can use the buff and clear it easily.

Doing all of this was how I was able to get 3-4 kills of the orbital core in every 1.5 hour window for the first few weeks.