Well, your IP block is possibly banned on the main Surpass server (probably by nothing of your own doing as I'll try to explain). Surmunity and I'm assuming Surpass Domains are on separate servers, so it's not affected. If you register, you should not be banned on the server your account will be on, because it will again be separate from the Surpass Hosting server where the website is.
IP blocks get banned when someone with a rotating IP address tries to abuse the server... Either by a DDOS or, as can be the case with the main Surpass server, sending in multiple fraudulent registrations. It often catches innocent victims in the crossfire, who have done nothing, but their current IP falls within the block. This seems to happen most often when you don't have a static IP from your internet service provider. Of course, I can't tell whether or not this is the case. It's speculation of what a possible cause might be. As far as I know, Surpass does not regularly ban IP blocks, only when it's especially necessary.
If you can register through a proxy, it should not affect your actual hosting at all. Your account will be on a separate server and as long as you aren't blocked from the Surpass network (which you aren't if you can get here) then you shouldn't have a problem. The issue that may arise is if you need to submit help desk tickets, and you will have to access this part of the site to do so:
https://desk.surpasshosting.com/
What you can do is submit a ticket to find out a better reason why you are having problems accessing the Surpass website. This community is mostly user-to-user, even though more staff are showing up every day (look out for the guys in the green... the rest of us are just customers, though the ones of us in dark blue, pink, orange or in my case, white are mods so we help out around here when we can)... You can probably get some tips to try and find out whether or not it is just a temporary problem on your computer and how to try and solve it (clearing your cache, maybe trying to do a tracenet... or something else)... I'm not particularly good at expressing that sort of thing. So I'll just try to stick with answering your question that you should be able to sign up through a proxy and it should not affect your account in any way. You should be able to access it like normal, and you probably won't have much of a reason to go to the Surpass site after you register, except perhaps to get to the help desk.