Those frequencies are allowed IF the device has been certified to comply with the rules and configured correctly and you are not interfering with any licensed user of that spectrum. MikroTik has not had the devices certified. Therefore it is illegal to use MikroTik devices on those frequencies in the United States. If you want to use those frequencies, you have to use another vendor. Get over it.
The FCC can fine you for use of those frequencies with non-certified hardware. The FCC has fined people for use of those frequencies on certified hardware which had been configured to use too much power or run old versions of the firmware which doesn't enforce the DFS avoidance requirements properly. So, thanks to morons who don't follow the rules, the FCC is making the rules more stringent and new hardware will likely end up being more expensive... The FCC, FAA, NOAA, and the US military get very excited when part 15 devices mess up their radar.
You have access to those frequencies if and only if you do not interfere with the primary and secondary licensed users of those frequencies.