The probability is not 50/50 for this case. By definition, the probability of any event occuring is that event(s) divided by the number of possible outcomes. So in this case we start with: Probability = 6 links/Total number of possible linking outcomes. Now given that it's more than likely each specific linking configuration has a different weighted chance to occur, the probability now becomes: Probability = Weighted probability of 6 link/Sigma (sum) of the weighted probabilities of all of the other linking configurations.

Mathematically: W6X6/(W1X1+W2X2+W3X3+W4X4+W5X5+W6X6)

Where W# is the weight of each linking configuration and X# is the number of links.

It's a common mistake for people to make the 50/50 case like you just did. In terms of probability when speaking of it mathematically, saying something has a 50% chance to occur implies that 1 out of every 2 outcomes is going to be a 6L because you always talk about probability in terms of the likelihood that a specific event is going to occur. Even if you take the 6L as one event and "not getting a 6 link," meaning any other linking combination, as the other single event, you can easily disprove that 50/50 is the probability by trying to six link an item. If it was 50/50, you'd get a 6 link half the time. Obviously this isn't the case.

Additionally, it is best to not call someone wrong before understanding the extent of the problem in question beforehand.

Source: Am an engineer by degree versed in statistics.