That's the best solution right there. Just don't populate those pins
If you connect the DB0-DB3 pins to ground and the R/W pin is ever HIGH and E is high, then the hd44780 chip will attempt to drive the pins (for sure when the chip is in 8 bit mode) which can create shorts on the pins if the chip is attempting to drive any of those pins HIGH.
I would level them disconnected.
But if you really want to connect the pins to something, I would pull them low through pull down resistors, rather than directly short them to ground. This will protect them should the R/W line and E ever both go HIGH.
I will say that in the 15 years I've been playing with HD44780 LCDS, I've never thought or ever bothered to test is if the DB0 to DB3 pins are still driven when R/W is HIGH and E is HIGH after the chip has entered 4 bit mode.
But even if the DB0 to DB3 pins are never driven in 4 bit mode, they will be driven in 8 bit mode, so there could still be a risk of a short if the pins are directly connected to ground, if R/W is ever allowed to be HIGH when E is HIGH.
--- bill
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