I personally have no issues even if it touches the RPi board, the flat cable is insulated. My RPi has now been running for weeks with no crashes and I plug and unplug stuff from it. Before I did this, it would systematically crash as soon as I would try to plug/unplug stuff.
For people worried about the cable being more bent this way, I don’t see this as much an issue unless you really force and fold the cable. The cable is quite flexible lengthwise.
The better solution would be to use a Dremel or file to enlarge the slot, but you need the tools and the hand.