Will merge mining patch make Bitcoin network mining power available to anyone?
The patch has no effect on the parent blockchain, it just allows the patched bitcoind to be used for mining on both chains simultaneously.  Only the child blockchain needs to be modified in order to support merged mining.  There's no way for the Bitcoin network to prevent merged mining, even if doing so were desirable.

Merged mining does have to potential to allow alternate chains access to greater hash power (and thus security against double-spend attacks) than they would have had otherwise.  However, this alone will not give them value as currency.

Bitcoin is able to sustain value because of its network effect.  The more active users it has, the more useful it is to each user.  The alternate blockchains have userbases that are a a few orders of magnitude smaller than Bitcoin's.  Newcomers to the cryptocurrency world will tend to choose the more useful and popular chain, further increasing Bitcoin's lead.