I dont see any problem with that..
I got one too and im currently using an iPhone to read manga on MD, not even using a PC.
Most likely as far as i know, the captcha is to check your connection whether you are a bot or not. I bet because the attack recently happen captcha is used to check all the suspicious connection and ensure that it is safe.
So, just do your captcha and you are good to go, it doesn't matter how many times you do that just bear it until the attack on MD is no longer happen. From my point, doing captcha is still better than having slow speed when reading.
Also, restarting your internet connection and stop using VPN instead using google DNS is good too, just sayin'