If you want to use a freeroll as practice for other tourneys, then definitely don't play the 1st hand push concept - because you're then trying to play like you would for a normal tourney.
That said, that is missing one of the main reasons for the post about pushing 1st hand: A solid strategy is a reasonable basis for your play, but sometimes you can spot other approaches as being more useful - aggression against people trying to limp into the money, calling more speculative hands when you know you'll get called if you hit your monster and push, taking advantage of specific structures (freerolls, 10 places paid equally like a satellite tournament, no-ante structures or high-ante/blind structures, kill games, etc). All of the structures mentioned are ones where a basic solid strategy may not be optimum and in some cases may even have a negative expectation. It's useful to have a basic strategy worked out, but it's at least as important (if not more so) to be able to look at different situations to see what changes you can make to improve your strategy.