[!.7.10] Help with player 'Slowfall'

I have an item that causes the player to 'slowfall', while wearing the item and sneaking. This code works as intended but after a few seconds (if playing on a server) the player is kicked for flying.

I am aware that I can set 'allowFlying' to true, in the armour tick, and false, in a tick handler. But I had some concerns about this and would appreciate some clarification.

Firstly, would setting allowFlying to false in a tick handler cause issues with other mods trying to grant permission for a similar reason?

Second, I don't actually want to grant the player the ability to fly, as this item is not intended to completely protect the player from falling or enable them to go higher, so is there a way I can prevent being kicked without using flight permissions?

If it makes a difference, I am using player.motionY to limit the player's falling speed, and ((EntityPlayerMP) player).playerNetServerHandler.sendPacket(new S12PacketEntityVelocity(player)) to update the player.

@Override
public void onArmorTick(World world, EntityPlayer player, ItemStack stack)
{
if (player.getCurrentArmor(1) != null && player.getCurrentArmor(1).getItem() == DTItems.rexoLeggings)
{
	if (!player.onGround && !player.isOnLadder() && !player.isInWater() && player.motionY < 0)
	{
		if (player.isSneaking())
		{
			if (world.isRemote)
			{
				world.spawnParticle("fireworksSpark", player.posX, player.posY - 1.5D, player.posZ, itemRand.nextGaussian() * 0.05D, -player.motionY * 0.5D, itemRand.nextGaussian() * 0.05D);
			}
			if (!world.isRemote && player.motionY < -0.1)
			{
				player.motionY += 0.1;
				((EntityPlayerMP) player).playerNetServerHandler.sendPacket(new S12PacketEntityVelocity(player));
				if (player.fallDistance < 1)
				{
					player.fallDistance = 1;
				}
				else
				{
					--player.fallDistance;
				}
			}
		}
	}
}
}