The main reason to have an IPS and a set asset allocation is so you don't time the market. But, "I think it is a bad time to own bonds but may do so later" is basically trying to time the market.
Also, the easiest way to rebalance, without any tax consequences or anything else tricky, is to use future investments. If you want money market funds, why not just put 100% of any new investment dollars into them until you are at your set AA? If that timeline is too long, at least consider doing that for part of that MM allocation. Then, when you get to where you want to be, all future buys should match your overall AA.
Lastly, if you have money in places other than just a Roth, consider where you want to put your lower yield holdings as far as tax implications. For example, you are better off with high yield bonds in a trad IRA (if you have it) because there is more expected growth and it will be tax-free, and muni bonds in your taxable account (as examples, and obviously REITs, small value stocks, or large growth stocks, or whatever else you hold would fall at various places in the middle of that continuum).