I think if he is spending enough time sitting in his high chair and eating, there is nothing wrong with snacks, or even the occasional meal "on the go". As long as he is not running through the house trying to eat at the same time (which could present a choking hazard), I think there are lots more things to worry about than this.
Of course, we only sit down for meals at the table about 3 nights per week. The rest of the time, if we are home, everyone crowds around the coffee table. Bad habit, but again, there are other things higher on my list of behaviors and actions to change at my house, kwim?