Are we talking about if ISX were allowed to trade tomorrow or if...

Are we talking about if ISX were allowed to trade tomorrow or if ISX were suspended until the conclusion of the ASIC investigation?

There's no point talking about if ISX remain suspended, as that does not uncover anything about why we are suspended today.

If ISX resume trading BEFORE ASIC finish their investigation, there are 300m+ shares on issue that may or may not become cancelled. As mentioned a number of times on this thread, if the perf shares are cancelled, the buyer of the perf shares may find his shares go missing and the ASX can be held responsible for those missing shares.

As mentioned many times, the ASX are not responsible for SP changes. That's entirely on the buyer.
The ASX are responsible for the trade execution (matching buyers to sellers).
The perf shares being investigated creates a problem in the area ASX are directly responsible for.

I'm not sure which part of this is hard to understand... should be quite straight forward and executives of both companies should be well aware that this problem will prevent the share from trading even in the best of conditions.