If you are going to sign a guy desperate to make the team, what can it hurt to ask for 2 years of team options? No matter if you even seen him play one minute?
Admittedly I'm not in the know with all the contract rules and whether not the NBA allows it. But if they do allow it then you should be doing it with every player you sign on a 1 year deal.
If your concern is you don't want to offend the player, then offer more in the first year to intice them. Instead of the minimum, double it. If the player turns out to be pretty good then you just got a steal on a player for the next three years. With no risk involved. You can bail by not picking up the option.
If it's possible to do then they should have done it with Mathews.