Is airplane mode with portable router more secure than using a sim card?

If I'm in a sensitive location, I use a portable router with airplane mode on but sometimes when I go outside its a hassel to carry the portable router along, I would much prefer to use a sim card, I'm not worried about tracking my location as much as I am with security (someone breaking into my phone).
Thanks.

    6 days later

    Sinai is your mobile router powered by sim card?
    What model do you use?
    And do you vpn or onion routing direct on the router?