Isopropyl Alochol has an exceptionally low boiling point. In a room at about 13C a spark will cause it to ignite (ie it's flash point is 13C). If some of this did wind up in your beer, it would
1. Be diluted to practically infinity (70% of bugger all is still bugger all)
2. Most likely evaporate very quickly.
We had a blend at my work that used this stuff and we had to completely change it because the risk is that on an average day in spring to autumn in Scotland, if we made this stuff there would be a huge risk of fire. If one of those wipe caught fire, it would be difficult, but not impossible, we were looking at about 4 tonnes...