A fried of mine is building a business and already has a squarespace website that she and her business partner set up but know they will likely switch to another platform like WordPress when they have more of their business identity fleshed out. I just help them with tech issues from time to time and will be the one to build their WordPress site when the time comes.
Recently, they have gotten feedback that their current Squarespace site is getting blocked by corporate firewalls and were wondering if a different CMS like WordPress would be less likely to be blocked? Because if so, they would have me start building their new site sooner rather than later.
That question I was unable to find an answer to using GoogleFu so any information would be helpful, thank you.

It would be the square space site was on the same IP as a site the firewall system didn’t like or anything like this.
WP you can self host. You don’t need to rely on an all in one system like square space
Question is why it get’s blocked?
Are people on that corp network able to access any other page?
Firewalls do not block platforms. In general, a firewall has no way to know what platform a site is built on. Firewalls usually block by category, IP, packet types, or block lists/thread databases.
This thing about corporate firewall blocking is a question for Squarespace support. As somebody else said they probably run your site on a multi-tenant server alongside some sites that firewalls block. Tell the squarespace people this is happening, because getting your site visible to your customers is what they do everyday for work.
People who run firewalls get their blocking rules from various services. Squarespace, and other good hosting services, have the business relationships with those services necessary to do their jobs.
A firewall that can tell by looking at your web pages that they come from WordPress, or Squarespace, or, I dunno, Geocities, is called a content-sensitive firewall. Those are expensive and hard to rig, and probably aren’t used to single out WordPress sites.
So choose the CMS that meets your business needs, and choose a hosting service with good deliverability.
BTW, deliverability is a big issue in email these days, but that is another story.
Generally, the issue you are facing is not tied to WordPress or SquareSpace. There are several factors to consider if you are being blocked by a firewall. Here are some of the one I can think of:
1. IP reputation – Make sure to whitelist the IP if it is blacklisted in any IP reputation blacklists.
2. Type of content – Since it’s a corporate firewall, I assume it will have built-in content filtering option. Make sure your site doesn’t fall into the category blocked by the firewall.
3. Security settings – Some firewalls don’t allow less secure sites like sites opening with only http, hsts etc.
4. CDN – If you’re using a CDN make sure you whitelist the CDN IPs in the firewall. Otherwise, assets from the CDN won’t load and the site may not work properly.
Hope this helps.
Some enterprise firewalls will block newly sites running on newly registered domain names.