Thanks to Aussie Susan! She replied at the above mentioned regex forum with the answer to my problem.
Here’s the code that’s working for me now:
static $anchorPattern = '/<a (.*?)href=[\'\"](?!javascript)(.*?)\/\/([^\'\"]+?)[\'\"](.*?)>(.*?)<\/a>/i';
I’m going to email the plugin author and suggest incorporating this change into the next release.