In reply to 8Blades:
The variable starting_phase is only set when the sequence is starting using the deprecated default_sequence methodology. Sequences defined for this methodology would typically run forever, so raising an objection in the pre_body() would result in the simulation hanging do to the objection never being dropped. At all other times, starting_phase is null.
As I said, you want to minimize raise_objection() and drop_objection() calls since they can have a significant performance penalty, especially if you run a sequence thousands of times. Since your test will encapsulate all of your sequences and ensure that every sequence has completed, you should only use objections at the test level.
Also, if you read the complete thread you referenced above, you will see that every response recommends not using objections in sequences.