I can see the argument both ways in regards using the bridge to support one's hand. Years back I saw Cliff Joyner use the bridge across the rails to support his bridge hand, and nothing was said. I thought it was pretty clever, and vowed to remember the technique if a similar situation ever came up.
On the one hand, just because the bridge manufacturers never thought that the bridge would be used in that fashion, or that it doesn't seem to be in common practice, doesn't necessarily mean that the bridge can't be used that way. On the other hand it does seem to be a peculiar and unnatural use of the bridge.
Yet it's not as if some special foreign apparatus is being used, like a tower of some sort. There are in fact some bridges that lever up quite high, and they're accepted. I even disagree with the use of special jump cues, or uniquely designed break cues. I've always used a break cue for rotation and 8ball break shots, but it was to protect my playing cue's tip from wear.
If the argument is that only the cuestick itself should be rested upon the bridge, what if I were to use a bridge that were, say, 8" wide, and then turned it on end? That would be traditional use of a bridge.
To take it further we might wonder why a tall man should have the advantage over a man shorter in stature? I used to play with a guy who was 6' 9". I never saw him use a bridge, whereas I, at 6' 2", had to occasionally use a bridge. Should we allow short people to naturally be at a disadvantage? Should we bar people of a certain tall height from playing because they have an advantage in reach? It gets silly.
It seems to me if standard equipment is used for the general purpose it was intended, then it should be allowed. Now, if someone pulled out the triangle rack and commenced to use it as a bridge, I would object...
