If your test is crashed during and after PCT, your PCT was not successful and you should definitely not be using an AI. Your PCT (SERM etc.) should bring you back into your normal range, if not slightly above. With all of the test boosters and things people use in PCT, there can definitely be a rapid elevation in estrogen and that level can get higher than your body is normally used to. This can put you at risk of estrogen-related sides if left for extended periods of time.
At the end of the day, if all of your hormones are within range and have been there for a decent amount of time, your PCT is successful and you may not have a need for an AI. Unfortunately, most people don't get bloods drawn during or after PCT so they are deaing with guesswork. In that case a good long taper on a SERM and light use of an AI is best, IMHO. A lot of what steroid users do is based upon guesswork and 'feel'. That is the nature of things it seems.
As I mentioned up above there just isn't one PCT protcol that will work for everybody. On top of that, the PCT protocols that any given indivudual has used in the past may not even be succesful for them in the future. Our bodies and their hormonal fluctuations are definitely moving targets. Without knowing excatly what our bodies are saying, we are all just making educated guesses. Sometimes an AI will be necessary and sometimes it might not be.
For me, I live with the motto that PCT is a time for normalization, while off cycle is a time for stabilization. Get your hormones within range during PCT and maintain that while you are off cycle. This is the safest best.
This is definitely a good discussion and the differences in opinion just show that there is no one size fits all approach to f*cking with our hormmones. This entire thread can be summed up in one sentence though - get educated, be prepared, know your body, get bloodwork and keep your hormones within your healthy range.