If the bike is your weakest discipline, then using this “time off” to focus on improving it is the smart move. I’m guessing your fitness is pretty decent right now given that you should have been building towards an IM in a couple of months. Therefore, the Sustained Power Build will probably be OK.
After that, I would suggest making up a “fake” bike race schedule and dropping it into Plan Builder…train like a cyclist for 6 months. Put a “B” event in early Septermber and an “A” event in November or something like that. Make them long road races vs. a short event like a crit so that the additional bike training will complement your long-term IM goals. Do a crap load of Sweetspot…
Still get in water (if you have OWS available to you) at least once a week to maintain your feel for the water and run easy at least 3 times a week (if not more). Look up the BarryP Running Plan as an option. You don’t need to run much, just consistently. Even short runs off the bike for a mile or two will be sufficient for now, with one “long-ish” run per week tossed in.
What IM were you targeting and what was your goal?