This is a brilliant suggestion actually. If I ever make a crypto messaging system I'll surely bake in a module that sends bogus messages to random nodes in the system. Then any sorts of metadata are useless to evil people.
> Pond doesn't transmit messages as needed because that would disclose when messages were being sent. Instead it transmits messages at random, whether there's anything to be sent or not. When there's a real message pending, it has to wait until the next randomly timed slot, which could be many minutes.
Sending packets to all contacts at random is a form of introducing white noise, vulnerable to signal processing techniques known and used from 1950s.
E.g. in case of biasing the method towards time of day, the attacker likely can filter it out using fairly basic statistical methods. Generally any kind of pseudo-randomization would render the method vulnerable; at least to the caliber of mathematicians which work at NSA.
If there's messaging system's own statistical analyzer, that learns your communication patterns and adjusts false messaging to rectify that, it could work. However the other messaging clients have to play along, which makes it fairly challenging problem.