In my opinion it is invalid. The reason being that it is specific in the rules that when two qualifiers meet, you state either Q1 or Q2: with Q1 being the qualifier listed first and Q2 being the qualifier listed 2nd. coolfish was very creative in his pick, and I dont think he was trying to circumvent the rule intentionally, but if his pick is allowed, you are opening a can of worms.
Here's my next FITD:
If Blake loses in first round, Then Lopez, otherwise Blake.
If Raonic loses in first round, then Kamke, otherwise Raonic
The highest rank player of the winners
The winner from the top quarter of the draw
The winner from top half of draw
All of these picks are definitive, but no manager would allow this, as it clearly stacks the favour my way. Same as picking highest ranked qualifier, it is stacking the picks to the favour of the person who picked this way. It is also unfair to EVERYONE else who picked according to the definitive rules.
I know you are trying to increase the fun, etc. But the decision to accept coolfish pick(s) should have been referred to the Board. You do a great job with managing, I'm not trying to pick on you. Just that the game has been running a number of years and any variance to the rules needs to be agreed upon by the Board. Also, if there are changes to be made to the rules, these generally get voted on during the off-season. That way each year, the whole season is standard and the same each week. The rules for all the games have been refined really well so there are little to no arguments on the results. If there is an argument, then it is obvious that something hasn't gone according to the rules, or something has been misinterpreted.