Potentially yes, in part due to many already held shares would be unable to be traded, then if good news hit only the shares available would trade thereby lessening the amount of shares in the market and the price could increase well, but not due to short covering because of the news and or symbol change. That is a perfect storm scenario you speak of and if you already own shares unless you buy and sell after all that happened you would miss it as well as many others :)
But yes if a large enough increase in price comes brokers can call for short shares to be covered
A sudden rush up in PPS at that time could cause a short cover. This would be speculation, but a ticker change, timed with a huge news report could cause a sudden spike up in price per share, correct?