Can I use my aviation handheld transceiver on MURS?
You asked for legal opinion, so the main "legal" reason would be that a radio must be type-accepted for the service for which you want to use it. So unless Icom A-24 is MURS type accepted, and it is not, then it's illegal to use it.

You don't need a special FCC license. FCC says this about licensing:


  MURS is licensed by rule. This means an individual license is not
  required for an entity to operate a MURS transmitter if it is not a
  representative of a foreign government and if it uses the transmitter
  only in accordance with Section 95.1309. There is no age restriction
  regarding who may operate an MURS transmitter.


But the transmitter itself must be marked as MURS transmitter. FCC has this to say about that:


  A MURS transmitter must be certified by the FCC. A certified MURS
  transmitter has an identifying label placed on it by the manufacturer.


There is technical reason as well which makes it impossible to use it on higher VHF frequencies: Above 137 MHz, the traditional modulation type is FM. Aviation VHF is AM. So even if you wanted to talk to MURS users, you wouldn't be able to do so normally due to different modulation types used. Another technical issue is frequency coverage. A-24 can transmit 118.000 MHz to 136.975 MHz. I don't know if it's possible to unlock it for extra coverage (but I'd be surprised is that was possible, due to use case), but with default frequency coverage you can't go high enough to reach MURS frequencies.

UPDATE:  I just checked and it seems that AM is actually allowed on MURS. So it is, and you can somehow unlock the A-24 to operate on those frequencies, you could technically speak to other AM MURS users, but again it wouldn't be legal due to licensing system used for MURS.