First please get some facts right! El-Salvador did not just make bitcoin legal tender but they made it the official currency. Mexico is not going to do the same! They are going to adopt bitcoin as a legal tender alongside their official currency system. So both cases are different.
I guess the point of the OP is that there will be a second country that most likely be adopting bitcoin. So that is enough for us to see this as a welcoming news.
That's a wise way to do it unlike El-Salvador! This way Mexico will be able to protect themselves from bitcoin's volatility while enjoying the innovation!
El Salvador knows the risk but they decided to gamble with it and go and make it a legal tender. Only time can tell if they are going to be successful or not. We are just in the bear market that's why many proponents or at least anti-bitcoin in El Salvador doesn't see any positive with the government's move.