As this is a discussion forum I shall persevere. The LDG WITH ABNORMAL L/G drill is ' for use when nose or main landing gear fail to extend and/or lockdown following the application of L/G GRVTY EXTN procedure'
Other gear problems have different procedures. For example TIRE PRESSURE LO - crew awareness. ie. normal landing.
Presumably the requirement to shut down the engines is to avoid damage/fire when the gear is not locked down and therefore is sure to collapse and taxying or staying straight on the runway is not an option. The assumption that gear that is locked down ,albeit with one wheel ,will collapse may be a consideration but only that. If one tyre is flat the above procedure is not expected to be used. If one wheel is missing and there is no procedure then airmanship dictates, and indeed shutting down the engines , with the consideration that the a/c may depart the runway just because of that is an option.
By all means follow the QRH procedure- just be sure you have the appropriate one.