I suggest that SRFI 170 get back the ability to ignore signals, which is much more straightforward than trapping them. Here's a proposal:
(with-signals-ignored signal-list thunk)
Signal-list is a list of signal numbers. Signals that are already ignored, cannot be ignored, or are being trapped by the implementation are filtered out of the list. The thunk is then executed under the control of dynamic-wind, using a before-thunk that ignores each of the remaining signals and an after-thunk that restores the default disposition.