No, synergy ability planning is an advanced technique which is not implemented.
Delaying heals on purpose to maximize the synergy output would require additional algorithms and goes beyond the scope of a generic rotation. If you wish to reach this level of optimization, you have to pause the Assist Mode and execute the delay manually.
GNB
Please note that it is impossible to waste Gunbreaker’s invulnerability.
Superbolide is technically the same as Hallowed Ground with the additional effect of reducing HP to 1. Even if Gunbreaker is healed, this ability still renders the tank impervious to damage for its duration.