This should do the bulk transfers using protocol 6.
The output here is now equivalent to the output of
usb_updater2 -d 18d1:501a -f
fwupdtool --plugin-whitelist cros_ec get-devices --verbose
Servo Micro
DeviceId: 84d0e3f2a0f8b2328f7995767b23ebb40494723f
Guid: 8e2f7625-a164-55d7-8f09-f193c8ec33f1 <- USB\VID_18D1&PID_501A&REV_0100
Guid: 13564257-c649-586d-b4e4-4f048d480f36 <- USB\VID_18D1&PID_501A
Serial: CMO653-00166-040491U00771
Summary: Servo Micro (aka "uServo") Debug Board
Plugin: cros_ec_usb
Flags: registered
Vendor: Google Inc.
VendorId: USB:0x18D1
Version: servo_micro_v2.4.17-df61092c3
VersionFormat: plain
Created: 2020-05-20
PhysicalId: usb:03:00:02