

Yeah, the interest idea doesn’t make sense, especially since for most of the 21st century the interest on savings accounts has been negligible.
If it cost $6 on the $1500 loan, that’s most (of not all) of the interest right there, and it takes time for that interest to accrue significantly. It’s not going to happen in a couple of days.
If this was the scheme, then your ex-boss was no criminal mastermind.
The chance of a payphone being handy in the middle of a demonstration is pretty small. If you have to run a half mile to find a pay phone, then the strategy starts to break down.
However, if you want to try this, maybe The Payphone Project can help you locate the nearest phone. According to the listing for my hometown, it’s likely a campground or cheap hotel.